I know it sometimes nearly breaks our  back to get under our van.
One good way to check out strange noises is to get right up next to a
long wall or building drive the car within about four feet of the wall. I
use the back side of Albertsons, they have a 10 ft high brick wall for
the full length of their building with no obstructions.

You'll hear almost anything that is bumping, popping or grinding this
way.

It doesn't hurt to have someone walk beside the car when you're doing
this sound location test.

Next test, put the car in 1st gear (if its a manual trans) or park and
try to rock the car back and forth by pushing it backwards or foreward.
CV joints should pop if they have slack.

Alternate: You can jack up one rear wheel, put the transmission in
neutral and make shure your brake is off and vigirously ratate the tire
in both directions and also yank it towards you and bump it in towards
the center. If you've got slop you should find it this way.

If you can't make the noise any of these ways you'll have to get under
the car.

You may want to check both tires on the rear for proper inflation before
you start any tests.

Stan Wilder
83 Westfalia Air-cooled