I have a nasty whine from back of truck not most of the time - not exhaust - worsens even with slightest increase on throttle. Vehicle is a 1500 4x4, '98. What's likely? diff? rear axle? bearings?

 

Have you checked your rear differential fluid to see if its low? This could cause noise.

How many miles are on your truck? Do you do much towing? Everything wears out over time.

Is your rear end a limited slip differential? Or have you recently changed your rear axle fluid? Limited slip differentials require a slipping agent for the clutches. If this is not added your clutchs will grab to much and cause premature wear and noise.

 

I just bought mine used, it is a 2 wheel drive 5.9L automatic? I know I have 3.55 gears. How do you know if you have a limited slip differential? Thanks Bill

 

My buddy lost a pinion bearing and it did the same thing. Check into it asap, he didn't and his rear driveshaft finally came out from the vibes/shaking making the straps break and took off the slip yoke on the back of the transfer case.

 

Any dodge dealership should be able to enter the vin into the compuer and print you out a sheet saying what all the truck has.

 

There should also be a small plate under your hood saying if you have limited slip. Close to the radiator i think.