Ok so i'm going to go and get me tranny and rear diff fluids change today. My friend is doing it for free. I think i'm going to go and put gm synchromesh into my tranny. What should i put in my rear diff? i have no idea

 

Amsoil synthetic 75W-90 gear oil in both tranny and rearend.

 

is amsoil synthetic better than redline synthetic?

 

amsoil is da bomb