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I'm in the hunt for a Dodge Ram, 5.9 Cummins diesel, 4x4, manual.  I live in Canada, and I'm planning 2 major trips (SW USA and Alaska). I'll be pulling a truck camper (about 1600 lbs. + gear = 2000 lbs.).  I'm looking for reliability (hardest thing is to find a truck that hasn't been abused!) and fuel efficiency.


Below are 2 trucks I'm currently interested in.  Is there one that makes more sense for the use I'm planning (pulling a truck camper most of the time):




I'd appreciate any help.





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First of all, a hearty welcome to the forums, Seb!  Glad you're considering a Ram/Cummins 4x4, they deliver a lot of substance in their segment, and I'm very partial to Cummins ISB engines when driven properly...


I looked at the first advertisement and can make a few observations.  The truck does not have exceptionally high mileage for a Cummins Ram truck, and I really like that its a 3500 series 4x4 for your purposes.  I'd like to go over this pre-owned truck's add-ons with some objectivity.  Here is the listed equipment:


1) 2006 Dodge Ram 3500 4x4 Mega Cab—This chassis is desirable if you need an 8' bed and Mega Cab.  Our '05 3500 is a Quad Cab with a 6.3' bed.  This means our wheelbase is only 140.5", where the truck depicted here has a significantly longer wheelbase.  Even with the SRW (single rear wheel) arrangement, you have a lot of turning radius here.  Towing would be very stable with this longer wheelbase, but so is a 140.5" wheelbase that can turn more sharply and does not require three tries to enter the local bank's drive through lanes.  Our short box truck with its auxiliary fuel tank in the bed would not be optimal for a camper or fifth wheel, although it's a great truck for a pull-type conventional trailer.  Depending on your plans, I would drive various wheelbase trucks before plunging.  You may prefer an 8-foot box with a slightly shorter Quad Cab.  Some prefer a dually for a very heavy cabover camper or 5th wheel—I would.


2) 5.9 Cummins diesel—Unbeatable, pre-urea era, '06 should not have a catalytic converter.  In the used market, you're better off with the 5.9L than an early 6.7L ISB Cummins.  Since this truck has the NV5600 (presumably) transmission, this is really a rugged powertrain by design.


3) Manual Transmission—6-speed manual, unbeatable*.  You do have the clutch concerns, but intrinsically, this is a good transmission unit, very rugged.  One concern would be the towing this truck has apparently seen, which is a load on the engine, transmission and axles.  I'll get into that subject.


*Frankly, had I known wife Donna would balk at driving our truck after the chassis lift, the oversized tires and a list of beefy accessories, I would have opted for the manual transmission when we purchased our truck.


4) 226,000 Kilometers—Around 135K miles in U.S. parlance, this is about right for most '06 trucks, neither too much nor exceptionally light mileage/kilometers.  The concern is what this truck did for that mileage.


5) SLT, Red, Power Windows, Power Doors, Power Heated Mirrors, Power Driver Seat, CD Player—Nicely equipped, appears to be a well maintained interior and exterior from these basic photos, a presentable truck.  Would guess that the truck was ordered by an individual or couple that wanted reasonable comfort and a nice trim package.  I like the cloth insert upholstery, our SLT package has held up very well.


6) 4x4 On The Fly—Nothing new here, if push-button, you have the same transfer case as our '05.  We do not use 4WD modes as much as you will at Canada and have had no trouble with this unit whatsoever.  Electronic shifting can be an expense in maintenance if there is a problem, however.  Most take this option for convenience; a transfer case manual shift lever would be just fine for me.


7) Lockable Canopy, Spray In Bed Liner, Hijacker Gooseneck Hitch, 5th Wheel Slider Hitch—This is where my eyebrows rise!  A clean truck, well equipped, this model was a hauler, and a heavy trailer at that.  Some would regard this as bonus equipment, I see it as extreme loads, possibly for much of the 226K kilometers of service.  The load on the entire powertrain and axles is clarified here.  Given the capacity of these two hitches, it's possible that every power delivery system on this truck could have been taxed heavily.  Personally, I don't see this as a plus but rather a telling story about the usage of the truck:  to haul a very heavy gooseneck trailer.  I'd want to know if these folks pulled a nine-horse trailer or a triple axle 5th wheel travel trailer.  If so, how far and how many times?


8) Upgraded AFE Turbo, Upgraded AFE Cold Air Intake, Upgraded AFE Intake Riser, Upgraded Turbo Back Exhaust, Bully Dog Programmer With Sensor Docking Station And Pyrometer—Surely this is a laundry list of high caliber upgrades that would cost a bundle to install yourself!  At the price of the vehicle, this would seem a bargain.  But it begs the question:  Why did the previous owner need all of this performance enhancement equipment?  Horsepower equals BTUs, and the only thing that gives me any comfort here is the pyrometer.  If used correctly, the pyrometer can reduce engine loads created by this added horsepower.  Any time you boost horsepower in a diesel, the cost is additional fuel consumption and heat impact on the engine, turbocharger and other underhood components. 


9) Upgraded front end ball joints, upgraded South Bend clutch and flywheel (about 25000KM)—Each are great add-ons that target weak links on these trucks when they are subject to continuous loading.  This again begs the question:  What was the truck's usage that it needed these components by 226K kilometers?  I like the individual upgrades but again wonder what usage this truck saw.


10) Will sell without Hijacker Gooseneck Hitch and/or 5th Wheel Slider Hitch—Possible indication that the previous owner wants to continue towing heavy trailers?  If so, do they consider this truck past its service/duty life for their needs?  Is it the previous owner who wants these hitch components?


Many would regard this truck and equipment as optimal for a serious hauler, and it obviously was.  The question now is how much life is left in the Cummins engine, the NV5600 or the 11.5" rear axle/9.25" front axle.  I've been inside each of these assemblies, and though high in stamina, they are not exempt from fatigue.  They wear out just like any other machinery, especially when continuously subjected to high loads. 


If I were to consider this truck, the cost of rebuilding the engine, transmission or axles would weigh heavily on both my decision and the purchase price.  I'd want considerable "padding" on the price, given the possible towing history of this vehicle.  More history of the vehicle's use, directly from the previous owner, would be valuable here.



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Hi Moses,
Wow! This answers a lot! Thank you so much for the welcoming message and all the pertinent information. If you’re having the impression to distinguish a French accent while reading, well, you’ve got it right and therefore I apologies in advance for (but not limited to :-) grammatical or lexical errors...

Bellow is the link to the other truck.


I assumed that the mega cab was using the long box frame but with a 6’3 box. Mega cab + 8’ bed start to be on the big side. Though not primordial in my decision making it still has some importance as I’m often on logging road finding small remote forestry camps and a shorter truck would make turning around a lot easier.
5.9 for sure
Manual transmission for sure: I like driving :-)
That was going to be one of my question. Manual transfer case or 4x4 on the fly? I use the 4x4 mostly to get out of slippery conditions (snow/ice). -25C (-13F) lately... and I’m in the southern part of Canada!
Truck is located in Alberta, surrounded by farm equipment, so I’m assuming a hauler as well.
Because I’m not well informed on the matter and from the abused trucks I see in my neighborhood, I have a tendency to stay away from all those adds on. The way I consider a diesel truck tends towards a tractor rather a Ferrari...
I see this a lot and I’m raising the same question: great this means I don’t (or shouldn’t) have the bad surprise to replace it for a while; but 250000 KM isn’t much for a diesel, how come those parts need to be replaced already?
Many would regard this truck and equipment as optimal for a serious hauler, and it obviously was.  The question now is how much life is left in the Cummins engine, the NV5600 or the 11.5" rear axle/9.25" front axle.  I've been inside each of these assemblies, and though high in stamina, they are not exempt from fatigue.  They wear out just like any other machinery, especially when continuously subjected to high loads.

To the comments above, I’ve been suggested (if nearby) to find a shop that specializes in diesels and has an oscilloscope to do a diagnostics (injectors, clutch, trany?) on it before buying. Any experience on this?

If this wasn’t enough, I also had a hard time finding information to differentiate the 2500 to the 3500 (lets stay on the 5.9 :-). I'm aware of the extra spring for the 3500; outside of this, not much. I've heard the frame is build with wider material, does it mean they are much heavier to start with; ie fuel mileage would differ assuming you’d drive them the same way?  
Do they use the same gear ratio?
Having the weight in the box, more carrying that hauling (1600 Lbs for the truck camper + 400 Lbs of equipment), would it be equivalent in fuel mileage?
Thanks again for all those tips; I have time before I buy but I also know they’re starting to be rare and don’t want to miss on the right one...

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Glad to comment, Seb.  As for "on the fly" shifting, the manual transfer case is also "shift on the fly" between 2WD Hi and 4WD Hi.  Transfer cases have been on the fly shifting in high range for many decades.  I like to back off on the throttle and finding the unloaded point when pulling the manual lever from 2WD to 4WD and when going back to 2WD.  This takes the load off the gear mechanism, and my transfer cases last a very long time. 


Shifting to low range with either manual or electronic shift control requires a complete or nearly complete stop to prevent gear clash and damage.  Some like the electronic push-button shifting as it eliminates some of the guesswork.  Again, electronic shift also has components that can fail, and the only troubleshooting inquiries on the electronic shift transfer case (273 type) that we've had at the forums were from Canada.  Could be the extreme cold weather.  I've had no trouble with my 2005 Ram 273 transfer case.


As for diagnostics and checking out the truck, the suggestion may have been a dynamometer test.  An oscilloscope is a diagnostic tool typically used for gasoline engines with a spark ignition system.  With an oscilloscope, you could likely check out the injectors electronically, and with some creativity, maybe even do a cylinder "dynamic" compression check by shorting out individual injectors and noting the drop in engine rpm.  (Dynamic compression testing is a function of traditional gasoline engine oscilloscope analyzers.)


The most realistic check for the Cummins 5.9L diesel engine, in my view, would be an engine drain oil analysis.  (Caterpillar and other industrial diesel shops offer oil analysis service.)  The lab results on the oil are very revealing, they show wear and engine damage quickly.  This is a cost-effective diagnostic approach without tearing down the engine.


Note: The oil analysis, which many diesel fleet operators do on a regular oil change basis, is considered valuable.  The lab/chemical analysis can find everything from bearing, piston and metal wear to gasket seepage, anti-freeze leaks or a cracked casting, all done by close analysis of the particles and chemicals in the drain oil.  Even low compression or poor cylinder seal leaves its traces in the drain oil, measured as particulates from the fuel blow-by. 


If you suspect a lack of smoothness or possible loss of compression or cylinder imbalance, a compression test would be sensible.  However, this test on all six cylinders can be somewhat expensive at a commercial shop.


Regarding frames, the 2500 and 3500 frame dimensions are the same.  The differences are in the brakes (sometimes), springs (definitely) and sometimes the driveline components.  You get factory clearance lamps above the cab on the 3500.  Here is a PDF on the frame dimensions for the model year 2005 Dodge Ram trucks as an example:


2005 Dodge Ram Frame Specs.pdf


As for axle gearing and details on powertrain/geartrain and axle ratio combinations, these are details for model year 2006 as an example:


2006 Dodge Ram Mega Cab Specs.pdf


I trust this is helpful, Seb...



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Oh yea, very helpful; thanks a lot Moses.

I'll keep in mind the oil analysis, looks like a great diagnostic tool. Will share the info if I get one done. 


Any opinion on the other truck? I'm not sure about the 4.88 gear. Just talked to the guy and it was used to haul heavier trailers; it was supposed to be a life time project and wasn't planning on selling it but he had some family issues...


As for the mega cab, just talked to the guy and this is his recreational vehicle; used to haul a 5th wheel for vacations.




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Seb...First, I would like to say that my comments are general and not intended to single out or target the current owners of either truck.  We each modify our trucks and trail vehicles to suit special needs, and each of these sellers has invested plenty in aftermarket "upgrades".  I'm sure they feel entitled to recouping some of that investment.  Many aftermarket upgrades, however, do not return much when you sell the vehicle.  That might be a topic for members to discuss...


The first truck with "vacation" trailering could use some clarification.  How many kilometers were towing kilometers?  What did the recreational trailer weigh?  There are triple axle 5th wheel RV trailers that weigh 18,000 or more pounds when loaded and going down the road.  There are also much lighter 5th wheels.  You would need to clarify the load.


Here is the other truck you're looking at, followed by some comments:


2006 Cummins
Yukon 4.88 Gears
New BF Goodrich 35's
New brakes
New rotors
Trussed Chevy 14 bolt solid front axle
4:1 Transfer case
Exhaust brake
Webasto Engine heater
4" Straight pipe with 5" MBRP tip
New dual disk clutch
New tranny
New windshield
1 ton suspension
Air Bags
Rev tek leveling kit
Etc etc truck can pull mountains or lift it and put huge tires...
Clean Clean truck


Attractive truck, couldn't see a mileage/kilometers statement.  Did I miss that?  As we agreed, a lot of "new" stuff means either a lot of use, heavy loads or higher mileage/kilometers.  New transmission and clutch?  Wow, the transmission raises questions, he obviously did haul "heavier trailers".


As for the 4.88 gears, you mentioned fuel efficiency, and this is definitely not the best gearing for fuel efficiency when cruising empty—even with the 6-speed manual transmission.  I have a 4.56 gear set with 35" BFG tires (actually around 34.6" if the All-Terrain KO).  My engine rpm running empty does not encourage optimal fuel efficiency unless I stick to a strict 65-69 mph range at cruise.  The closer to 65 the better, around 1980 engine rpm. 


The 6th gear on the manual NV5600 is 37% overdrive (0.63:1); my truck's 48RE 4-speed automatic's overdrive ratio is 31% (0.69:1).  As a result the 6% extra overdrive would make 4.88 gears very close in engine speed to my truck with 4.56:1 gearing.  With 37% overdrive in 6th, the 4.88 gears would spin the engine around 2000 rpm at 65 mph.  At 69 mph, the engine would be spinning around 2125 rpm.  This is nearly identical to my engine at these road speeds and would be governed by exact tire diameter.


The good news is that this 4.88 gearing did offset the hefty loads pulled by this truck, somewhat reducing the strain on the engine and transmission.  (Strain on drivelines, axles and brakes would still be high.)  This gearing would work with 37" diameter tires, though a taller chassis lift would be necessary.  If my current lift is sufficient, I'd like to try true 35" or 36" diameter tires on my truck with the 4.56:1 gearing...I'm told by AAM that there are now 4.30:1 gears available, unavailable when I chose between 4.10 and 4.56 for the 35" tires.  4.30:1 would be my choice today.


Cummins fuel efficiency has been covered in detail at these forums.  Join the 30,527 viewers, as of today, who have made this one of the hottest forum topics to date: 




When running empty, the 4.88 gearing at cruise speeds would spin the Cummins engine too fast for optimal fuel efficiency.  On the other hand, and I considered this with my gearing choice, this gearing would be quite good for towing a trailer mostly at 65 mph (maximum of 70 mph)...


Sorry to make you constantly convert to kilometers, Seb...force of habit!



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Hi Moses, 


The fuel millage/gearing choice is how I came across this forum... as for the conversion to Km, thanks to Google it's as easy as a click of a button  ;)


Well, I'm heading this weekend to take a closer look at the 2006 mega cab.

In addition to all the AFE upgrades, according to the seller, all injectors have been replaced a couple years ago. I'm guessing the only way to confirm this would be to see a paper trail?


Also I'll be needing new tires (which I don't mind as it gives me an insight on how they wear out and if something is "off balance"). The ones installed are stock size (265/70/R17). Is there any other tire size to consider that would not translate into an increase in fuel millage (the gear ratio is the original)? I'm considering Goodyear Wrangler A/T Adventure Kevlar (E rating) as it can do a bit of everything: road 80%, gravel road 20% (which is close to what I'm estimating driving) and has the snow flake symbol (which became mandatory here in BC).


Any tips on particular sounds I should or should not hear when starting/test driving/shutting down the truck? 


Thanks again for all your insight.

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Hi, Seb!  The injectors on these engines are electronic assemblies, and the 2004.5-2007 system is a common rail EFI.  They seem to present less trouble than the earlier Cummins injectors, so parts receipts here should be enough proof.  If purchased new, these injectors can be quite expensive!


Tire wise, I lean toward the new BFGoodrich KO2 All-Terrain that we tested at Baja in September.  This is a breakthrough tire with extended wear capability, the "snowflake" rating and a very strong sidewall wrap with advanced tread and sidewall rubber compounds.  The KO2 tire has been tested by the media at Canada, look for reviews from a few months ago.


The least hassle will be the OEM size tires, there will not be a speedometer error, and the tires will match the gearing.  My very best fuel efficiency with our Ram 3500 was with the stock size OEM tires (happened to be BFGs) that did not alter the gearing or, more specifically, the tire revolutions per mile.  Load Range E is a must for whichever tire you choose.


As for noises, the very nature of a diesel engine makes it difficult to hear engine "knocks"—the compression piston rattle is a continuous knock!  If you suspect engine bearing noises, the best test is the drain oil analysis, capturing the drain oil properly for the test. 


Watch the engine oil pressure.  I expect over 40 psi within seconds of startup cold.  Idle oil pressure will drop when the engine warms.  Don't compare Cummins oil pressure with a gasoline engine, especially an AMC/Jeep design inline six!  What you want with oil pressure is consistency once warmed.  The pressure should hold at whatever is "normal" for idle and road speeds. 


Here are the factory recommended oil pressure specifications for this 5.9L Cummins engine.  These are minimum pressures.  Again, I like to see over 40 psi at 2,500 rpm and at least 20 psi at idle.  The minimum pressures listed are low in my view:


Engine Oil Pressure (MIN)

At Idle 68.9 kPa (10 psi)

At 2500 rpm 206.9 kPa (30 psi)


The rest of your testing on this truck is straightforward.  Check for clutch slip, "chatter" or roughness on take-off.  Listen for gear noise in any gear(s) of the manual transmission.  Check for driveline "clunk" or axle ring-and-pinion backlash noise.  Listen for axle bearing noise or gear whine under acceleration, "coast" and deceleration.  Stock axle gears like 3.73 or 4.10 should be quiet when compared to 4.56 or 4.88 aftermarket gears.


Note the brake response for true, straight stopping from higher speeds.  Check the steering return-to-center after corners and for excessive steering pull left or right.  When checking for steering pull or drift, be objective; try for a flat road surface, not a dramatically tilted or cambered road. 


Check that all options and accessories work.  Ideally, factory installed equipment is best, as there is less fear of wiring issues or poor connections, which often get hidden behind the dash or worse.  If aftermarket equipment is in place, check for proper installation and function.


The truck should accelerate well from idle to 2,500 rpm.  Beyond that speed, the 5.9L Cummins is just spinning itself out, although horsepower continues to climb and should feel strong at 3,000 rpm.  "Redlining" (3,400 rpm in this case) these engines is pointless, though some do this when they have no idea how to drive a diesel.  You have a whopping six manual speeds with the NV5600 transmission.  Whether testing the truck or driving it as an owner, use the gears! 


For maximum fuel efficiency from a stock Dodge Ram 3500 5.9L H.O. Cummins engine and an unloaded truck, I would be upshifting the manual transmission at 1450-1600 rpm. Loaded, I would strive for 1,600-1,900 rpm shift points whenever possible.  Grades, passing and so forth, the stock H.O. will pull strongly past 1,900 rpm, you could spin the engine at 2,400 rpm or higher when necessary or for safety sake. 



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