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I suggest an AMC/Jeep . 4.0L , or a 258 cu. in. Parts are everywhere and reasonably priced . Couple that with a Torqueflite trans and a 8 3/4"Mopar , Dana 44or 60 , 9" and you have a winner IMO . Just remember a 4.0L doesn't have a mechanical fuel pump but does have F.I.

Not planning on changing up rear end.
A lot of good ideas coming out here.