89pickupsr5

there is a 4 inch lift with no modifications to the drive shaft it was bought the way it is and now it is making a ping/dunk noise when put into gear(it's an auto)
when accelerating it makes no noise as soon as you let go of the gas it rattles the same noise but faster. we drained the rear diff fluid and refilled it and there is no metal in the oil. to me it sounds like it is coming from the drive shaft.

thanks, drew

904_runner

The "clanking" leads me to believe you have a u-joint going out. My mom's automatic did the same thing. It would clunk when you put it into gear.

i dropped the drive shaft and felt the movement of the u-joints. It turns out that one, the rear iirc, was completely dried out (thanks non greaseable u-joints).

Noltz

X2 on the u-joints. When loaded, the shaft is driving the rear yolk. But when coasting, the yolk is driving the unloaded shaft, and the play becomes apparent. Pretty simple job... did 1 rear joint in about 40 mins with a hammer, sockets and a vise.

DYNNOMMYTE

X3 on the joints... but you wont know unless you crawl under and look..

axman667794pickup

x4 the joints, ive had the same symptoms on my 94. the rattling will keep getting worse until u fix it or drop the driveshaft hah.

Junkers88

Something else to mention here is if you plan on replacing the worn u joint then replace all of them, on both drive shafts. Then keep the two that are the least worn for trail spares, I'm willing to bet the front pair is in good shape so plan on keeping those. Also try to buy joints that you can grease and hit them, and every other grease point, when you do your oil change.

bigarms23

check u-joings and yokes