What do you mean by you can "hear" a wobbling noise? Do you mean you can feel a wobble, or can you hear a grinding, chattering, clanking, pounding or other type noise? Have you checked for loose lug nuts? Sometimes it's always something simple.
I guess you might raise the car (on jack stands) and see if the rear axles have too much play in them, like pulling on the wheel to see if you can push and pull the axle, or see if you have an up and down movement with the wheel. Maybe check for excessive play in the driveshaft at the universal or yoke. I once had a tire losing the tread on the inside side of the tire which caused a pounding sound. Good luck, I know what a PITA this kind of problem can be.
sounds to me like it could be any of the following;
1) check your Universal joints, could be loose or worn.
2) check for play in the rear axle bearings (jack up rear end and see if you can wiggle the back wheels around by grabbing them and jiggling) You get play ? you got worn out bearings in the axle (cheap to fix)
3) Pinion bearing is worn out, allowing too much play. Replace bearing. If you leave this problem too long it will destroy your Ring & Pinion Gears.
4) Ring & Pinion are shot (this is probably the worst case scenerio) and you must replace them and all bearings in the diff.
Hope this helps. Start with the cheap & easy stuff and eliminate those possible issues 1st, then move on down the list.
Mach1steve
I say axle bearings. Our 77 marquis used to go woowoowoowoowoowoowoowoo when driving. You can't feel it, but it sounds like a kinda highish-pitch wobbling sound.