The thrust washers in your transmission should be changed during a rebuild. Replacing the thrust washers will allow you to bring the end-play of the transmission back to the original or tighter tolerance. OPT carries both full thrust washer sets and individual thrust washers. Some of the kits OPT sells do include selective washers or shims to adjust the end play to the desired clearance. If you are buying transmission parts to rebuild your transmission, don't forget thrust washers. Replacing the washers could be the difference between a transmission that lasts for many miles to come, or requires an overhaul prematurely.