GM-39743 is used with a press to install the mainshaft bearing and the countershaft extension small bearing.
GM-39473 contacts the inner hub of the bearings to prevent any damage to the outer bearing cage.
GM-39473 is used as a press adapter for the countershaft small bearing.
GM-39473 is placed onto the inner hub of the bearing, and used with a hydraulic press to fully seat the mainshaft bearing or the countershaft extension small bearing into place.
GM-39473 also is used to protect the front end of the shaft when servicing its components, and may be used with GM-39442 to protect the back end of the shaft.