TH400 Turbo 400 Billet Case Saver Snap Ring Support 34761AC

The GM TH400 (Turbo Hydramatic 400) holds its center support in the case with a single large snap ring seated in a machined groove in the aluminum. That groove is the weak spot. Under hard launches, towing loads, or the added line pressure of a built unit, the center support hammers back against the ring, the ring pounds out its groove, and the case cracks or the support walks. Once that groove is worn or broken, the case is usually scrap. This billet case saver is the fix builders install before that happens.

It is a machined billet aluminum ring that installs behind the factory center support snap ring, spreading the thrust load across a wider bearing surface instead of concentrating it on the thin edge of the cast groove. That takes the pounding off the aluminum and lets the case live behind more power. It carries GM-interchange part number 34761AC and fits the TH400 / Turbo 400 from 1964 through 1998, including the units behind Chevrolet and GMC C1500, C2500 and C3500 trucks.

Installation happens during a rebuild or when the case is apart: pull the tailhousing and rear internals, remove the center support snap ring, drop the case saver into place behind the ring, and reinstall. It adds no clearance changes and needs no machining. If you are freshening a TH400 that is going behind a bigger engine or a tow rig, this is cheap insurance against splitting a case you cannot easily replace.