I use Mobil 1 75 - 140 full synthetic in the diffs., quiets the whine down a bunch.
And Mobil 1 4T Racing 10-40 synthetic in the motor and subtrans.
Shifts quietly and like butter.
I also use 75w-140 Mobil 1 gear oil in both front and rear diffs and 0w-30 Mobil 1 engine oil in the sub-trans. Welcome from Mississippi @Hemiplymouth. I like your screen name!