Plainview

Yesterday while driving my truck on the freeway something in the tranny, t-case, or maybe the rearend started making bad noises.

At freeway speed its like a really harsh and loud buzzing or very rapid knock but as you slow down it becomes more of a pronounced knocking. Its not the engine - its vehicle speed and load dependent and doesn't matter what gear your in or what RPMs the engine is turning the sound is the same at any given speed.

The transmission still shifts fine through all gears and the noise is the same in all gears.

I suspect tranny or t-case just because of where it sounded like the noise was coming from while driving on surface streets with the windows down, and also because you can feel the knocking in both shifters.

I got under the truck and the u-joints are fine. There is no play at the pinion shaft on the diff but there is a small amount of play at the t-case output flange and there is oil leaking there and being sprayed on the underside of the truck.

How can I determine exactly where this noise is coming from?

I need to get this fixed ASAP for as little money as possible. I'm thinking if its the T-case that maybe I can swap another one in from a wrecking yard for now then rebuild this one at my leisure, but the main thing is to get this fixed and working reliably by the end of May.

I'm thinking of putting the truck up on jack stands then starting it and putting it in gear to see if I can hear better where the noise is coming from while outside the truck...? Only thing is, it doesn't make much if any noise when not under load.

Any help/suggestions appreciated!

rust bucket

I would recommend checking the support bearing assembly. I had a similar problem and it was the culprit. With the truck in neutral push on the driveshaft where the two rears are joined together and supported by the carrier, chewed up rubber and play are signs of trouble.