Any ideas what would cause a high pitch whine, seems to only be noticeable when in high gear and under load, it goes away when you let off the throttle. Do not hear it except in OD.

Rearend bearing?

 

maybe torque converter.

 

sounds more from back

 

Well I did a full 4wd service todat. Put Royal Purple 75w140 in both diffs, the old oil looked pretty good, i cleaned them out with spray cleaner and the gears all look great and no metal shavings in either. No idea on the whine unless it is a drvieshaft / ujoint issue. Transfer case looked great too, oil was clean replaced with Mopar ATF+4. Guess I will drive it and see what the deal is maybe fresh oil will quiet it down.

 

my buddy has the same problem. had it checked several times and no one could tell him what the problem is. it runs fine..