i have a 97 ram 1500 4x4. i am hearing a whining coming from the rear of the truck, i took my wheels off and looked for axle seal leaks behind the drums and there are no leaks. I also checked the diff fluid and it was of good color. as far as a know they guy i had bought it from did something with the gears because i see some sealer coming out of the diff cover. this noise happens when i am going forward starting at about 20 mph or so, and gets louder the faster you go.

were the gears swapped?
the sealer (most likely RTV silicone) is probably from removing/reinstalling the cover, could have been from swapping gears, or just a simple fluid change.

to me, it sounds like either a bearing is going bad, or the gears weren't set up correctly, and are wineing. if it were me, I'd pull the cover off, and check the fluid for metal, and check the wear patern on the gears.

also, dose it have a LSD (Limited Slip Diff.)? if it dose, it could be that no friction additive was put in when the fluid was changed.

yea it is a limited slip rear, and i was thinking it would be that the guy never added that friction additive. but if i am gonna have the cover off and everything apart, i might just replace the bearingsa while i am in there. do you think if the ring and pinion were off-set, would it make the same kind of noise?

possible front pinion bearing, or side diff bearing. If limited slip additive was not added and the fluid level was correct it would chatter around turns not whine.

if you're going to go ahead and replace the bearings, you might as well do the entire axle wile you have it apart. you'll need to get the bearings for the carrier, the pinion, and the outer axle bearings. you'll also need the axle seals, pinion seal, and a new crush sleve. as long as the gears don't have any abnormal wear, you can reuse the existing shims.

about 6 months ago, a guy that I work with had basically the same thing happen to his truck. the dealership forgot to put in the friction additive when they changed his dif. fluid. basically, the clutch packs wore out, and the particles chewed up the ring and pinion gears, and it started to wine.