use 3.90 or 4.11 with the 700R4. 3.08 will be fine with the TH350. The 10 bolt will be fine unless you plan on really giving the truck a lot of abuse - then I would use a 9" Ford, which is pretty bullet proof. My buddy has the 9"Ford with 3.90 and the 700R4 he puts his foot into it all the time and hasn't broken it yet.