This is a replacement input sleeve for the 5-speed Getrag transfer case. If your input sleeve has worn splines, it must be replaced to prevent stripping the splines and the consequential costly failure of the central differential viscous coupling unit.
Installation requires a hydraulic press.
NOTE (for '91-92, 18-spline only): If the transfer case has a bolt in the middle of the cover near the "e" in "Getrag", then you need a "large bearing" sleeve. If no bolt then "small bearing".