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Am thinking that this might be a dependable and different/unique ‘swap’ for an older truck. I have a 1939 Hudson 112 Model 90 pickup (pending rebuild/restoration), and think that the Cummins R2.8 w/AX15 (2WD/RWD) trans would work well together.

Have made inquiries to both Cummins, and to Advance Adapters. Nothing from Cummins as yet – other than the automatically generated emails. I did get a response from Vic Carroll (Advance Adapters). They do not market or have access to a 2WD AX15 transmission (?), however they appear to be in the midst of expanding trans adapters for the R2.8 (?).
It is a bit ‘early on’ in the rollout of the Cummins R2.8 diesel engine, hopefully Advance Adapters will follow through, expanding their offerings for ‘adapter kits’ for other transmissions.

The ’39 has manual center steering (as manufactured). At present, I am trying to determine the ‘weight difference’ between what the truck came with (175 cu in flathead inline 6) and the Cummins R2.8. The answer (when it comes), will have an effect on what direction this whole thing goes in – which (besides engine) might well include the front suspension, steering, etc.. I figure that there may be as much as 200 LB difference in weight – however that is pure speculation at this point.
The rear axle is, in my opinion, ‘toast’. Parts to rebuild it are just about impossible to obtain, and even if it were done – it would most likely not hold-up to the increased power / torque. Luckily, there are several differentials that would ‘fit’ under the rear of the truck, only requiring minor modifications, and would be more than adequate to handle the power/torque – and even have the same wheel bolt pattern/measurements.
Another of the ‘major issues’ is that of the AX15 transmission (no ‘new’ 2WD version available) – so selecting a workable transmission would be another stumbling block (and possibly flexibility between trans type (Auto/Manual).

Currently, planning on this project is purely thoughts, ideas and discussion(s) – almost nothing is ‘set in stone’. In-and-of itself, It is very daunting to a gray-haired Army retiree (stubborn fart, ‘older than dirt’ – LOL!)…

Other than planning and thoughts, I have done very little with my '39 Hudson 112 Model 90 pickup truck.  I am still contemplating what to put 'under the hood', and how I am going to go about doing it.  The Cummins R2.8L is, from my 'first look' a somewhat good 'fit' for reliability, power, and will be more than a bit unique in comparison to the normal SBC shoved between the rails of most 'restorations'.

I say I have done very little, (cleaning and repairing a few pieces), however, I have bought a scale - to weigh some of the Hudson engines I have in my workshop - just to see how they will compare (weight wise) with the Cummins R2.8L engine.  That (the weigh-in) is coming, hopefully soon - but have other basic things to do around the workshop, in preparation for beginning to do 'projects'.  Am also anticipating the 'shoe to fall' - i.e., the release & sale of the Cummins R2.8L, which was due earlier this year (delayed, due to CA emissions testing/qualification (?)).

The 1939 Hudson 112 Model 90 Pickup is more than somewhat unique and rare - try finding one, in ANY condition.  An internet search will find a few - and you are sure to find pictures of my pickup truck among those images.  Most of what you will see are NOT the Model 90, but the Model 98 (Big Boy, 3/4 ton), and you'll likely only find a couple of them.  My estimate is that there are less than 20 of these pickups left, in ANY condition.

When I have a chance, I'll post a few photos of my Hudson pickups - yes, pickups.  I have four at the moment - two (2) 1946 Hudson Pickups, and now two (2) 1939 Hudson Model 90 112 pickups (just acquired a second one, out of Colorado - last week).

1939 Terraplane Project PU.jpg




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39HudsonPU...Thanks for sharing your project!  The R2.8L would be an optimal swap for your 1939 Hudson 112 Model 90 pickup! As a purist on restoration and bent on preserving the integrity of older vehicles like your Hudson pickup, I would personally focus on motor and transmission mounts that would not in any way modify or mar the original frame: At a later date, the truck could be brought back to pure stock with no scars or obstacles. This compact, self-contained engine would provide the engine-driven resources you might need, including a vacuum source, alternator, fuel pump and starter. Short in length, the engine could be carefully positioned for clearance at the radiator and firewall, beefing up the radiator and cooling system to handle the increased BTUs of the diesel engine…Currently, the transmission choice could be an AX15 five-speed or an automatic transmission that Advance Adapters has targeted.

Yes, this is a feasible, exciting and worthwhile swap into a vehicle that does not have emissions requirements. At the same time, the engine is high tech and emission efficient, an optimal crate package for your vintage pickup. The Cummins R2.8L engine has powered a Nissan Frontier concept pickup, a Brazilian F350 Ford truck and a variety of popular 4x4s. It would be great in your Hudson pickup…If you do follow through with this swap, please share the details and progress at the magazine’s forums…I’ll open up a vintage pickup section for your truck!
I have made many powertrain swaps into vintage vehicles without marring the frame. The first was a 1955 Ford F100 pickup. In my late teens, I converted the F100 to Pontiac V-8 power using Ford truck manual transmissions (first a straight stick then an overdrive version) and also a dual-coupling G.M./Pontiac Hydramatic. The truck evolved with a small-block Chevy V-8 to Ford truck manual 3-speed with column shifter. Each swap left room for a complete restoration to unblemished stock mode if desired.

TransDapt’s period adapter kit (purchased from J.C. Whitney in 1968) was well conceived and provided a stout “bolt-in” approach for these engines to the stock Ford frame and cross-members. I learned from that engineering, and this insight has followed me since.

Please share detailed photos of your pristine Hudson frame (ideally with the engine removed), we can discuss ways to make the R2.8L Cummins diesel a bolt-in and safe swap, using either the 2WD version of the AX15 or an AW4 automatic. Advance Adapters has also talked about a G.M. 700R4 adapter.

Note: Cummins will supply the engine package seen in the magazine’s video through the Cummins Repower program. The R2.8L crate engine package with its “turnkey” approach should ease any conversion.  See the video at:  http://www.4wdmechanix.com/advance-adapters-and-cummins-2-8l-diesel-engine-conversion-for-jeep/.

I’m familiar with everything on your Hudson from the steering gear and rear axle to the transmission and engine. I would guess that the R2.8L four is not that heavy. Cummins concentrated on a powerplant for trucks like the Nissan Frontier that would have limited load capacity up front.  You might find that the original suspension works well enough, and if a beam axle with semi-elliptic springs, you could have custom springs made to support any difference in weight. If the steering gear is Ross or Gemmer, we’re talking stone age with limited parts other than those that interchange with more popular applications. Then there’s the originality factor again, you hinted that a street rod was not your aim. I’m sure Hudson buffs would agree.

What are your plans for the steering gear and rear axle? Of course, you’ll convert to 12V electrics, but even that can be done to near stock appearance. Your truck is very cool and worth preserving!


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