HELP!!!!Put in 8 3/4 rear and it vibrates real bad

loganscuda said
Ok wheel looks like it warped when turning, but the wheel is not swapped wheels still does it. But It looks like it is the drive shaft. Son put driveshaft on and where the u joint goes on is 4 1/4 inch which is 1 inch bigger than my u joint in width. What kind of car would this center section come off of.

It is a B body 8 3/4 out of 66 charger.

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I have another one that is the same as my 8 1/4 was.

That's why I was curious about the drive shaft. If you replaced a 7 1/4 with the 8 3/4 the drive shaft, for one thing, it would be too long. It might be possible that something got forced out of shape when you put the weight of the car on it and drove it.. I would also look closely at the tailshaft on the trans to be sure it's not damaged.

There are combination U joints that will fit your driveshaft AND fit the larger yoke on the 8 3/4.