When it comes to full-size 4x4 trucks and SUVs, the General Motors Turbo-Hydramatic 400 (TH400) ... thanks to a steady supply of rebuild kits and replacement parts offered through the aftermarket.

TH400 Transmission Rebuild - Trans-Former. HOT ROD Staff Writer Jun 07, 2010. See All 18 Photos. ... For that, we skipped over the popular TH350 in favor of the stronger TH400.