The pinion seal on the 218 mm RDM has a sealant applied around its OD, and the output shaft seal on the 195 mm RDM is a larger diameter than the current GM seals. This sealant requires a higher installation force than previous seals. GM-50871 is a steel seal installer instead of plastic, due to the force required to drive the seal into the RDM carrier. Plastic seal installers will not deliver the installation force required to seat the pinion seal, and GM-50871 was originally developed for the Camaro HP 250 RDM, which has a very high installation force, requiring a metal seal installer. GM-50871 fits both Alpha RDMs, and installs both the 218 pinion and 195 output seals. Used with GM-22828 Installer.