Originally Posted by stingc

TH400's are notoriously inefficient. The only good thing about them is that they are really strong. A stock truck isn't going to need that strength, so going to a 400 over a 350 will just make it slower.

I don't really understand the aversion to overdrive. If you want to drive around without it most of the time, just leave the shifter in 3 instead of D/4.

Also, TH350's have a higher 1st gear than 700R4's, so your low speed acceleration will suffer. Then there's the extra fabrication needed to make a 350 fit. This doesn't seem like a very good idea.