DS balance, pinion vertical plane vs. tcase vertical plane (as mentioned...).
U-joint condition too, you'd be surprised what that can do with no other symptoms.
I generally shoot for 2* down at the rear pinion, as there is usually *some* axle wrap even going down the highway. Regards your front noise, I get that too, but because of a long travel spline (some play is inherent and it acts a bit like an unbalanced shaft).
Heb Dduw, heb ddim; Duw a digon
I'm that gun-totin', farm-raised, evangelical, pro-environment, OHV ridin'/drivin', Southern civil rights pro-labor Liberal yo' momma told you couldn't possibly exist.