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Jackson

Vintage Willys Pickup Axle and Transfer Case Upgrades

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Dear Sir:

I have a 51 Willy's pickup with a 4.3 Chevy motor, SM-465 trans and unfortunately, a NP-208 t-case presently. Wanting to change out Timken rear W/5.38s and Dana 25 front. Where I reside not much junkyard stuff to choose from. In your opinion, what would be the most reliable, reasonably strong, and ease of install that I should chase. Vehicle will be used predominately on back roads America. Some steep Jeep trails,and 10-20% freeway time. Hate this computer crap. If this goes through, Thank you very much!

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Hi, Jackson...Very interesting, classic Willys!  The 4.3L Vortec V-6 should be reliable, adequate power.  Please share your tire diameter, I'll make some suggestions about the axle ratios. Before suggesting front and rear axle types, I need to know which transfer case you will be using and the "drop side" or differential location for the axles (offset left or right).  The transfer case will determine where your front and rear axle/differentials need to line up.

Moses

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Hello Moses, Thank you for your response. My tire diameter is 33 x 10.5 x 15 mudders. My t-case is a NP-208 presently, looking to change down the road. It is a passenger side drop. It is so difficult to look towards the completion of the project when parts availability, and sudden oops factors arise. Many questions still to come, One step at a time. If we ever meet  I'll definitely buy you a cold one.

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Hi, Jackson...The correct T-case drop will dictate your axle choices.   You have a number of transfer case choices.  If you want rugged, a gear drive Advance Adapters Atlas II or an NP205 gear drive unit would be top on the list, each right side drop.  The common 1980-86 Dana 300 is also right side drop and stout enough for a vehicle in the Willys Pickup weight category.

Cost effective axles can be a set of leaf spring Dana 44 or GM Corporate types from the disc front brake era, matched to the T-case drop.  The wider track width is desirable from a safety/center-of-gravity aspect.  Use that to advantage.  A vintage ('71 to pre-IFS '80s) GM, Dodge or I-H leaf spring axle set and matching transfer case would simplify the conversion.  You'll need to reposition the spring perches to match your Willys springs, correcting front axle caster and rear axle pinion angle.

A good ratio for your axles depends upon your transmission.  If you stick with the 33" tires and rugged SM465 (one of my favorite units!), you have no overdrive.  Since first (compound) gear is very low, you can get by with taller 4.10 gears (even 3.73s if the engine is strong enough).  This would offer good performance overall, great off-road performance in low range and 1st gear, and an okay highway ratio for the 33" tires.

Moses  

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