Take your time, have a clean and "happy" work space, ideally a jig or at least a big table vise to hold the pumpkin for torquing bolts. Are you changing the ring and pinion? For me getting the pinion depth right is the biggest pain, big time-saver is to gradually sand/grind the ID of an old outer pinion bearing so it slides on and off the pinion by hand for checking until you get the shim stack right. I think there are some how-to articles on here on rebuilding 3rd-members.