What does it involve to replace the rear differential mount on my 85 300 SD as my tires were wearing poorly and think this will help.

The differential mount will have a somewhere between zero and imperceptible effect on tire wear. The only connection to the wheels is through the axles and those can be removed and still roll the car. Bushings, subframe mounts and so forth would be better places to look...things that can affect the rear wheel alignment.

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

If you are having rear tire wear, a more likely problem is worn trailing arm bushings. It can be a little difficult to see how bad they are until they are unbolted and lowered.

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Sam

84 300SD 350K+ miles ( Blue Belle )

Agreed.

Unfortunately, I have also concluded that it has an imperceptible effect on ride height as well.