Make sure the shim package is on the side gear, position the carrier with the ring-gear flange facing down, and insert the side gear and clutch pack up into the ring-gear side of the case so the clutches don’t fall out. Rotate the case 180 degrees and insert the second side-gear pack. Now slide the Posi over the axle stub in the vise, holding the upper side-gear pack in place. You must align the two pinion gears before rotating them into the case to ensure the cross-shaft will slide through both the case and the pinion gears. The final step is to back one pinion out at a time to insert the thrust washer between the pinion and the case. Tom prefers the steel washers to the OE brass versions. We used one of Tom’s hardened cross-shafts.