I have a TH350 as well but mine is 4 wheel drive with a np205 transfer case, Im looking to add quite a bit of power soon I'm looking to generate around 450 hp with 470 tq, Im not sure if the TH 350 or the 400 will be good for getting the poer to the ground, I do have a preformance kit for the 350, but not sure which tranny would be better??