Loud rumbling sound from rear

[Kossykoss]

Hello everyone. This is my first post here.

I recently brought this 91 ranger back from the dead after it was abandoned for 5 years. It’s a 91 4.0 automatic rwd with the 8.8. It’s finally running and driving pretty well except for this loud rumbling from the rear. It usually happens when taking off from a stop or accelerating hard. Gear oil was changed recently and it didn’t look too great. There were thin metal shavings in the oil. Not an insane amount but enough to be worrisome. The diff has 109,000 miles on it and from the diff tag it’s not limited slip. I’ve check underneath the truck and nothing stands out too much other than the driver side axel having some up and down play. I’m hoping the diff isn’t dying. Anyway…here’s the video of the sound. If anyone can give me some advice that would be awesome. Thanks!

 

[rusty ol ranger]

If there are metal shavings in the oil somethings eating itself back there.

I cant tell much from the video.

I would at minimum pull the diff cover and have a look. Drop the driveshaft and see if the pinion bearing wiggles.

Good news is its pretty easy to swap rear ends. And they arent super expensive in a junkyard...and being 2wd you dont have to be concerned with axle ratio

 

[sgtsandman]

Being that it is happening during acceleration, it's probably not the bearings on the wheel side, but if you are having issues with the differential bearings, you might want to consider changing them as well since they use the same gear oil to lubricate them as well.