Try unbolting the rear driveshaft at the yoke and rotating 180 degrees and then bolting it back up, worse or better, if worse, rotate it back then go to the front driveshaft and do the same thing. The drivelines in AWD Astros are dynamically balanced, each component as a rotating unit, meaning the whole driveshaft is balanced together, yokes and all and while bolted into the vehicle. Anytime u-joints are replaced, the yokes must be marked and put back in the same orientation and they must be bolted back in to the diffs in the same orientations. If you suspect it may be a transfer case issue, pop open the fuse/relay box under the hood at the master cylinder and pull the 10a fuse labeled ATC (transfer case) then test drive again. Be sure and inspect everything that rotates, there should be a weight on a sleeve at the rear diff just behind the yoke. Look for any sign of a weight missing on any of the rotating parts. If any of this doesn't help or helps some but doesn't eliminate it, I can try to scan the balancing procedure from my service manual to help solve the trouble, it is slow but the only way to balance without all the high tech gear the factory has. I know my front driveshaft is in good shape but the transfer case has slop in it at the front output shaft. I have been running with the ATC fuse out for a couple years now with plans to put an S-10 transfer case in which will give you 2 hi, 4 hi, and 4 low and a neutral position. The front driveshaft has to be modified but parts are A LOT easier to find for the S-10 case and other than the front driveline and the wiring for the 2/4 selector switch, it is a bolt in.


'85 GMC Shorty
'98 Suburban K2500
'98 Pontiac G8 GT
'77 Pontiac Astre
'95 Jeep Wrangler
"I thought you weren't allowed to talk to guys with vans??"