I'll be shopping for a 545RFE or 65RFE for the auto trans to replace the 5-speed manual trans for my eventual 56 Dodge pickup build on my 2001 Dakota 4.7/RWD chassis. Shopping on CL and FBM makes it easy to find a lot of used trans, but many of them are for 4x4 chassis. My truck will be RWD only.

So if I buy a 545RFE or 65RFE with the transfer case attached can I simply remove the transfer case and install the u-joint for the driveshaft? Or is there an additional end cover/seal I have to use to convert a 4x4 trans to a 4x2 RWD trans?

Also, the build will require a new/custom length driveshaft when I get to that point. Should I use steel? Aluminum? Carbon fiber? My primary goal for the build is to create a totally modern and current/new chassis under my 56 pickup so it will be as "new" as a brand new truck for a LOT less money than buying a newer used truck.