you should use the stock rubber on the upper rearend
or are you changing the bushings on the control arms?
Control Arm Bushing Tool This Bushing Tool (Part #0599) is designed to remove AND install the bushings into the top ears on the rearend housing. This tool is made to fit GM housings, and may fit others as well. The design includes a roller bearing thrust washer for ease of use and long life. The Bushing Tool is also plated for rust prevention and appearance. The Tool PULLS the bushing out and also PULLS it into the ears, and does this in under 2 minutes with an air ratchet. Ask anyone that has done this the hard way, and they will tell you this tool is a life saver. Hours of aggravation can be avoided with this new tool. Some generic pullers with adapters to fit (hopefully) your application are over $400! Our tool is designed specifically to work on GM rearend housings for sure, and possibly others as well.