Once the cluster gear was in place, we inserted the countershaft, lightly tapping with a brass hammer as needed. The trick here is to not displace any of the roller bearings inside of the cluster gear as you are installing the counter shaft. If you do, simply remove the cluster gear, reset the roller bearings, and try again. We got it on the second try. We also cleaned the front counter shaft bore and added a tiny bit of black RTV to help seal the case before tapping the countershaft into place. We also dapped a bit of black RTV on to the countershaft bore on the other end of the case once the countershaft was installed.