Oil for rear end

[richardkillmon]

What is the best oil to fill the rear end of 1976 MCI 5B challenger.

[luvrbus]

GL-5 85-140 is backwards compatible for older gear lube, works great for the MCI 5 with the drop box, buy a 5 gal pail it will take most of it to refill the differential and drop box.I buy the Valvoline brand because it is easier for me to get from NAPA not that I think it is any better