Ok,

Truck is completely stock with 198K miles on it.. L33 engine, 4x4, stock tires, stock gears, stock tune, stock trans. 85% highway miles... I picked it up cheap due to miles and since then this issue has shown up..

It is really a mere annoyance at this point but i will see if anyone else has had an issue like this..

It occurs on part throttle shifts at traffic lights.. the 1-2 shift occurs, then there is a thump.. not a noise a feeling.. like someone hit the frame with a rubber mallet.. Not harsh but not soft either.. There is about a half second delay from shift to thump.. I have been under truck, mounts appear to be ok (from what i could see late in the evening) and after that it doesnt do it again until you stop and it goes from 1-2 again..

Any ideas???

 

ujoints?

 

Have yet to pull the shaft but just looking at them/ checking for excessive play they seem fine..

Will pull shaft tonight and report findings..

 

It's the famous Gm clunk. Take your driveshaft out and grease the crap out of the tail housing. That will last awhile. I plan on cutting a bounce ball in half and putting in there so its not hitting metal.

 

Is that the same as the ford no grease clunk.. Just the slip splines on the Driveshaft binding...

Is it actually bottoming out or is it just binding and unbinding on the slip??

Thanks