rearend noise

I have noise on deacceleration only once in awhile,I've flipped rearend but did not shim it. Was wondering if this is the problem or do I have a bad pinion bearing.truck is 80 chev shortbox half ton.thanks

wat kinda setup you runnin. i had a truck that the drive shaft was hittin the in put shaft housing of the tranny because the rear end was set up wrong

its the pinion angle, you need to get shims.