nasty shaking while braking

[dgumoe]

Back again for more help. 95 ecsb 5.7 4l60. I lowered the ass end of the truck 4 inches with the djm shackles and hangers back when i had the bed off for body work. I havent lowered the front yet as i didnt have the money for the spindles. The truck shakes like crazy in the rear when slowing down. Its usually only in town under moderate braking. If i jam on the brakes it doesnt do it. I tried using just the parking brake and the truck doesnt shake at all which leads me to believe the rear drums are not warped. I just put drop shocks on it hoping that would help. It didn't. With a 4 inch drop do you think i need to shim the carrier bearing? Or does the pinion need to be rotated down. It appears that the rear diff is aimed straight forward possibly up a bit. I dont have a pinion angle tool to check it yet. Ujoints and carrier bearing are all tight. And i dont have any unusual vibrations any other time. Any ideas?