I cheated on mine
Carried the parts up the hill one at time and bolted them onto the vehicle as I went. Most of it was manageable but the planetary gears weigh a ton.
You can tap the spacers or shim plates between the hull and the brake plates once you know the final drive center is bolted up properly. I think they were designed to allow easier fitting of the unit onto the hull at production. That way minor variance in the welded body panels wouldn't cause issues when everything was going together.