Go the 4BT forums.
they have all the answers you need, and anything that fits the back of a 4 cylinder also fits the back of the 6.

There is a recent thread about the 3053A http://www.4btswaps.com/forum/showthread.php?t=2168

A 3053a requires a divorced transfer case, I don't think a 205 is? To use the 205 then the NV4500 is the best choice, faster OD than the 3053A, and everything fits with standard dodge tuck parts.

I did not realize that you have a 4X4, and is it only a 1/2 ton?
If so then you probably should start with a stronger frame for the 6BT, and a Dana 60 front axle to stand up to the weight.

If you do have a 1/2 ton I would forget about the 6BT and go for the 4BT.

Again, join the 4BT forums, search the past threads, or read a bunch of them, and ask questions there.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-