A common failure in the 4T65-E Transaxles is the wearing down of the splines on the 4th gear clutch shaft. The stock shaft is not intended for high power applications or aggresive driving and in some cases will wear out completely resulting in the complete loss of 4th gear.

Our clutch shafts are hardened and will resist this problem.  Please note that 2003+ vehicles will already have this shaft installed.