Thanks for the replys to my post earlier. I was getting ready to pull the axles, and my father in law mentioned I should check for missing driveshaft weights and make sure the universal joints weren't loose before resorting to something so drastic. Well, I crawl under the car and sure enough I see that the rear universal had moved, so that one of the caps was sticking out slightly (instead of being against the lip on the pinion to keep it in place). As a result the whole u-joint had slid to the side. I loosened up the ubolts and put everything back where it went, and fired it up. The vibration was gone! I don't know how it managed to move, but that was definately the problem. I'll keep an eye on it to see if it moves again. Thanks for the help /forums/images/icons/smile.gif