Here is the noise: A whining sound sorts like gear noise
Symptoms: speeds above 30mph but only when engine/drive train are not under load, ie. not accelerating or crusing. Its just noise no vibration it occures in neutral or drive with and with out overdrive on. Seems to be speed related. I can hear it less at 70 and most around 45 to 55.
Other info. The ujoints and drive shafts have moderate rust there are no lube fittings on the ujoints and I changed the gear oil last summer(yes it is still full). There does not seem to be a lot of lash in the gear set either. I am stumped. U-joints seem to be up to par and the hubs are not hot after driving a long distance.
Oh yeah the sound started when I was running 70mps on the interstate and had to break really hard to avoid an accident. I heard some banging around but that was likely a few boards in the bed sliding up to the front of the bed.

Any thoughts???

 

I just had a similar issue with one of my axle joints, It wouldn't move around by hand but what I did was put it in 4 wheel drive and raised one wheel at a time and rotated the tire front to back and the joint was loose. You might try that for your shaft, raise the rear and have some rotate a tire and watch the joints.

 

I dont have 4wd, I did lift the truck and have a friend rotate the tire everything looked normal well execpt for the heavy rust on the ujoints and shafts.

 

any one else have an idea?

 

How are your rotors. I had some whining noise at 40-50mph and it ended up being my brake pads rubbin on rusted rotors. Just a thought. Could have over heated your pads and possibly warped your rotors if you breaked overly hard from 70mph.

 

could this happen to drums? the noise is 100% in the back/under the truck.

 

I have a similar issue. But I hear it usually hear it above 30mph. I belive it to be a carrier or pinion bearing in the differential. Do you have a LSD?

 

I know you don't have 4 wheel drive, I was just suggesting you try to the rear what I did to the front to check the joints .

 

yes it has lsd. Zman all the joints seem to be good from what I can see.

Pinion bearing?.......great

Its going to the shop today lets hope for a cheap fix........stay tuned

 

Did you try pulling the brake drum off (in rear) take a peek in there. Maybe your self adjusting pin at the bottom is hanging off.