TH350 - Goodbye!

The original hairline crack near a bolt hole. Likely the result of mismatched hardware or over-torquing.

The TH350 has a solid reputation as a “bulletproof” three-speed. It’s a favorite in the hot rod world because it is relatively lightweight and can be built to handle massive amounts of torque. Despite its reputation, I noticed a small leak coming from a crack in the case back in 2018.

A quick fix with some JB Weld. It’s not the prettiest repair, but it held up and stopped the leak for years.

While the transmission never actually failed me, the lack of an overdrive gear was a constant bottleneck for the “Turbo 250” project. Running high RPMs at highway speeds isn’t ideal for a built daily driver. I decided to start the hunt for a 1992 700R4 - the “holy grail” of the overdrive era.

Finally pulling the TH350 out to make room for the 700R4 swap.

One interesting note on this specific transmission is the “K” stamp found on the case. In the GM world, the “K” case is the heavy-duty version, often found in trucks and 4WD vehicles. It features a thicker casting and extra ribbing for strength, making it even more desirable for a performance rebuild.

The transmission and torque converter are headed to the Marketplace. It’s time for this project to finally get an overdrive.