Ok, this thread is for a friend of mine with a 68 ss. His TH350 just shot craps so he are looking into a TH400 or a 700r4. He is leaning towards the 700r4 but has no idea how much work would go into swapping that in (and neither do I). Anyway, how hard would it be? Would he need a new drive shaft? What stall would you recommend? Would there be any advantages to a TH400 over the 700r4? Any advice would be appreciated, its his baby and he wants to get it running again.