Install on an 8.8 requires a press to be done right. Everything is set with shims, and you can't just pile them up. The side shims need to be one piece, so if you can't re-use the ones that are in there you need to figure out the size and order them. I've done a couple hundred installs and they can be super easy or a major PITA. I have a bag of both pinion and side shims that I've collected over the years.
Also, the crush sleeve for the pinion gear preload can be a bear. It requires like 275 lb-ft to crush the sleeve to a certain bearing preload, and it's probably 8-10 full turns from contact to finished. If you go too tight you start over with a new sleeve. Getting the picture? I do mine by 'feel' with an impact gun, but I can also 'feel' a .006" backlash without a dial indicator.
This is not the place to experiment unless you can afford to have your car down for a lengthy period of time, have gobs of extra money to pay somebody to fix it, or don't mind gear whine.