Best axles for 3.9 4BT Cummins swap

So I am planning on swapping my old tired F head for a 3.9 4BT Cummins with an allisson auto.

1) will that setup fit in my 1958 CJ5?
2) the Cummins weighs about 400 lbs more than the F head. I need to upgrade from my current Dana 27 and 44 combo. What would be best for this setup?
3) would the transmission be too long to fit?

Thanks.

 

The quickest is "anything is possible with time and money". Is it a good idea? Nope. The amount of engineering that will have to be done to fit that beast into a short nose willys will be huge! Plus, auto transmissions are ridiculously long compared to manual trannys. More than likely, you'd have to switch out the front fenders and hood with an intermediate ('72-'75) just to get enough room for the engine. As you mentioned, the weight will be a huge concern, as will pairing a tranny and transfer case combo that won't give you a 6" driveshaft.

If you are stuck on a diesel, I'd look into swapping a VW tdi, or get one of the kits to swap a kubota engine with your current t-90/d-18 combo. Check http://overlanddiesel.com/Diesel_Conversion_Photos/Pages/Kubota_Jeep.html for more info.

 

The Allison auto will leave no room for a driveshaft as it is twice as long as your t90 and then some.

 

Never gonna work without turning your Jeep into a rock buggy.

Allison autos are nice, but unless you're gonna haul a 25 foot boat on the trail, there are other effective choices for an ECJ.

 

Not only do the axles need to be replaced, but the frame will need significant reinforcement or replacement. Longer wheelbase, more cooling... you're better to start off with something like a fullsize truck...

 

Fellas,

Thanks. Your replies confirm my suspicions. Now I have a great excuse and idea for a new project! I think the 4BT would go nicely in an M715 or similar truck.

 

Good idea. Plenty to read on the 4BT being done in the FSJs. Much better idea.