i have 65 mustang v8.left rear wheel has wobble when jacked up and in gear.checked at the rim.moves about 1 inch in and out.looking for a axle.does anybody know whats same as a mustang rear.has anybody had this problem.high speed vibration.

 

Sounds like a bent axle flange. Remove the axle and take it to a machine shop. They can spin it for you and tell you if that's the problem. They may also be able to straighten it. Or maybe your wheel is bent. Either way it sounds like that rear end got squirrely and some one curbed it.

 

Helped a guy the other day with a '66 replace both rear axles in his eight inch. He didn't recall hitting anything but one was slightly bent at the flange anyway. Left side too, coincidentally. Slight wheel wobble and definite high speed vibrations. The other axle was fine, he chose to replace both with new ones. I would have just replaced the bent one. He said they ran him about $130 each, didn't say where from though.
Good used antique Mustang axles (or some that will fit) aren't exactly dropping out of the trees. You might post a wanted ad here and on other Mustang oriented forums. Somebody might have one lying around. I happen to know where there's a good used right one, but that's no help.

 

put the wheel off the other side on it first to make sure it is the axle not the wheel, if it is the axle they are hard to find and even if you do who is to say it is better than yours . 2 aftermarket axles probably 250ish