Drivetrain 97 cobra 4.6L rear end vibration

boricua007! said:

The cover plate of my differential has grinding marks on it from the ring, what has or is causing this.

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Pics of the differential cover. Sounds like it was damaged and dented inward.

Is the rear original to the car? It's kind of a hard thing to hit with road debris but a hard hit in the rear could drive, say, the sway bar into the axle; if the rear is from another car do you know its history?

Back of the car vibrates when going at high speeds, is that causing the vibration?

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If the rear has a collision history it may have bent axle flange(s) or tubes. Vibrations at high speeds generally points to an aforementioned flange problem, a wheel/tire imbalance or a driveshaft balance or pinion angle problem.

Does the car have the factory control arms? If not, are the uppers adjustable and if so, are they properly adjusted?

Is the iron damper (that large piece of seemingly useless iron under the pinion) still in place at the front of the pumpkin?