I have a 98 Cherokee, 4.5 inch lift with 33s. Maybe a month or 2 ago I was driving and it started roaring when i gave it gas, only it goes away when i let off the gas. It still does it to this day. It changes with my speed, but its only when im giving it gas. When Im slowing down to a stop it does it from maybe 10 or 5 mph to stopped. Its an offroad rig but i drive it on the road sometimes just for fun. Its getting worse and worse the more i drive it. Its sounds like a rear end noise. Maybe bad pinion bearing? Its a Chrysler 8.25. I just had the rear driveshaft out and grabbed the pinion yoke and checked it for play. It had a little bit of in and out play but i couldnt tell if it had any up and down or side to side. The play was very minimal, maybe less than a 1/16. It almost felt like it was supposed to have that much play. Any help would be appreciated!

 

More likely carrier bearings if the pinion is tight. Even if the fluid looks good. How many miles on the rearend?