When HPP teamed with GM Performance Parts (GMPP) and Classic Restorations to mate the new THM 4L85-E SuperMatic transmission to a built-to-the-hilt SD-455, we wanted to fully document the process.

•Previously, we took you through the necessary steps for installing a modern electronically-shifted 4L60E trans into your third-gen. But we only got you half way there. This month we made a trip over ...

With stand-alone control of electronically controlled overdrive automatics, it's easier to dial in accurate upshifts, and you can just stab the throttle, steer it, and the trans will do the rest. The ...