ah..now I understand where you're coming from. But...not to get too far off topic, but for purposes of this discussion and owner's intended power output I feel that's a point of debate. I frankly prefer the TH350 over the TH400. When built properly (very inexpensive and easy to do) the TH350 can be built to handle substantial HP & torque, and with it being lighter in weight with much less rotating mass it is more efficient and allows more HP to get through it to the ground. TH400's waste HP.

Given 2 identical cars, if properly set up, the TH350 car will be slightly quicker and faster than the TH400 car...and will get better fuel mileage. Both will have equal service life and handle the abuse equally well...AGAIN only if properly built and set up, maybe to a max of 600-ish horsepower.

Indeed in pure stock form the TH400 is stronger than the TH350. And the TH400 can be built to handle MORE than 600 hp...where that's approaching the limits of what a TH350 can be built to handle.

I run a TH350 behind my 400 engine F-bird...I dumped the TH400 by choice...