The boss for each end of the cluster gear is inside each end of the transmission case, and they are different. We made sure that the outer thrust washers on the ends of the cluster gear were matched with the correct case boss. You do not want to put them on the incorrect side. You may find it easier to use a little grease to hold those thrust washers onto the boss’ to ensure proper alignment and drop the cluster gear in separately. As long as they are in the right place in the proper orientation, it doesn’t matter if you stick them to the boss’ or to the cluster gear for installation.