wrote
A friend of mine has a 2000 blazer, 4.3L with auto, 46,000 miles, and a
> clunk at the rear end when the gears engage. I looked and saw alot of slack
> as the rotation of the driveshaft seemed excessive before the engagement was
> met in the rear differential. Like the pinion is out from the ring gear a
> bit. The universal joints were replaced last week. Thanks in advance for all
Don't get too excited about some play back there. There is more then just the play between the ring and pinion. You also have to account for the play in spider gears and their pinion shaft, play between the spiders and the side gears in the differential, and slop between the side gears and the case, and side gears and the axle shafts. Unless the pinion is loose, or side bearings are worn allowing the ring gear to move back and forth...the play you are seeing is probably normal.
Ian