After getting my car back together after a clutch swap, it now seems to clunk when running at low speeds when the gas is tapped a few times (on-off-on-off-on-off, etc). I checked the torque arm and it looks solid. Rechecked all tranny mounts and they look good too.

I then fiddled with the driveshaft. The diff side is tight, but there is movement on the tranny side. If I push STRAIGHT UP (no torque or turning) it moves about 1/32 - 1/16". If I shake it up and down, it will lightly clunk. I think this is the culprit.

Now the question, can this be taken care of? I am guessing that it didn't happen before because of the old fluid and the deposits on the splines kept it tight. But now with clean splines and clean fluid, It is a little loose.

 

I doubt it's the splines, sounds more like a shot u-joint to me. Easy replace costs about $10.

 

I thought the same thing, but the clunk occurrs when I push on the tranny side of the U-joint. The driveshaft seems solid in the U-joint.