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

loganscuda said

I just installed an 8 3/4 with new bearing and 355 gears and at about 30 mph it shakes really bad what the heck is going on. it is real bad.

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Pretty vague info.

Did you rebuild the unit? How about pinion angle? What car? The more info you provide the better for someone to hopefully narrow things down for ya.