Alright I want to change the oil in the front diff, rear diff, and transfer case. Its a 1996 Chevy K1500 with the stock 10 bolt rear end and manual transfer case. For the rear I am going to get royal purple max gear synthetic 75W90. For the front im thinking regular old 80W90 gear oil. And for the transfer case im going to get royal purple synchromax. Will two bottles for each diff and two bottles for the transfer case be enough? Any tips or things to watch out for? I know im going to have to reseal the rear diff with some atv sealant thanks yall.