My 98 RC 4 X 4 has had a slight buzzing / grinding sound in the rear end for probably 80k miles. Its gotten progressively louder, when it started, I could only hear it with the back glass open. I've never really been able to isolate it. It only does it between 40 to 55 or so mph under load. Below or above that range or coasting you can't hear it. No play in driveshaft, pinion, or anywhere else that I've found. Made the noise with old transmission, makes the noise with rebuilt transmissions. Sooo, I assume it is pinion bearing or the pinion on the ring gear making the noise. I work at a junkyard and can pull another axle with the same gear ratio off a ram and swap it. I have read that the axles on vans are set up from the factory with tighter tolerances to reduce the possibility of noise since the cargo area in a van acts as a sound amplifier. I believe I read this on Randy's Ring and Pinion websight, and they offer different R and P's for vans and trucks for this reason. If I do swap axles, should a pull an axle off a 2 gen van with the same ratio to get a better chance of eliminating the noise? I assume the rear axles are the same on half ton vans and trucks (they look the same), other than the previously mentioned tighter tolerances. Anyone have any insight on this? Will be a bit of trouble to merely eliminate that noise, but its finally gotten loud enough to annoy me if I have the radio off.

Also, I took it by a buddy's shop. He said he thought it was the pinion bearing making the noise and the axle would easily go another 100k....but damn that sound chaps me.

 

Measure the width of the axles. I think the van axle was narrower??

 

Will do. Don't know if they're the same width or not. Good idea, thanks.

 

Yeah the van axles are a couple inches narrower. I was gonna pick a 3/4 ton van axle up from the local pull a part but when i measured them they were a bit off.