1997 Ford Ranger, 198K, noise in the rear and slipping

My dad’s ranger just started making a loud noise in the back of the truck and constantly feels like I’m driving over speed bumps. Can anyone steer me in the right direction? I don’t want to get ripped off at repair shop or spend more on the truck than it’s worth. The universal joints feel tight, could it be anything in transmission or rear differential? THanks in advance for helping a struggling college kid!

Try jacking up the truck so that both rear tires are off the ground. With the transmission in neutral, try rotating one the tires back and forth while watching the U-joints. If there’s any play in the U-joints, this test will reveal it. Doing this will also reveal if there’s a problem in the differential.

Tester

Wheel bearings are also a source of rear end noise, if he bearings have deteriorated to the point it causes the feelings like speed bumps it is time to prepare for some parts replacement. You can pull and push on the wheels to see if there is any play to check the bearings but if it is as bad as I read you need to have it towed to for service or diy quick!