I have a 02 ECSB with a 2 inch drop shackle (no hanger). Its been on there for about 2 years now, no vibrations no nothing. Recently my carrier bearing started making alot of noise.

So we replaced the Ujoints and the carrier bearing.

And there comes the vibration -- 40mph it starts and cleans up around 80mph. Worse on the freeway.

I never shimmed because I never had a vibration.

What we have done so far:

Used both 2 and 4 degree shims, with the fat end pointing both directions.
Moved the carrier bearing bracket backwards and forwards.
Used a completely different drive shaft off my friends truck.

--

What else could it be? It did not present until we replaced the carrier. My old one had a TON of slop for about 70k miles. Never had a single bit of vibration.

Do I need a carrier relocation shim with just a shackle drop?
Is my frame bent?
Do I light it on fire?

Thanks.