I've got a 00 F350 SRW 7.3 AT. No lift with stock tires. The rear has been getting louder and louder over the last 3 months. It only makes the "noise" wich sound like I have a supercharger starpped on to the rear wheels, under load ie, on the throttle or gearing down onto off ramp etc. I have changed the oil and put in friction mod. Pinion bearing?

 

Hi Wade,

While it certainly can be a bearing, it sounds to me like an abnormally worn ring gear. Does it do it all the time you're under power, or only under power in a certain speed range?

 

ALL the time. As soon as power is going to the rear wheels. It stops when I let the hammer off, but as soon as the truck catches up, its back again. I am realy thrown off by the lack of a shimmy, shake, or anything else. I seems normal except for THE NOISE.