What is the difference between the 700R4 the TH400 and the TH350? which engine setups work best with each of the tranny's? 700R4 sounds like the best tranny to me simply because it has the highest number, but anyone got a better answer than that? my blazer orignally had a 700R4 but it got swapped for a TH350, on a 305 motor. we gotta get the tranny rebuilt tommorow, just through a Jasper 305 in and the tranny went out on me. thanks