This only seems to happen after or during a right hand turn.
It sounds like two heavy metal parts banging against each other.
I almost suspect the diff, but it 'feels' like it's coming from the transmission area. Any ideas?

Also I finally got my probuilt rebuild trans installed, and at cruising speed it howls. Not real loud, it sounds similar to a diff howl when the two gears no longer mesh perfectly. It's particularily noticable with the TC locked. Is that something to be concerned about?

 

The clunking may be the exhaust pipe swinging and hitting the driveshaft.

Pete

 

could also be somethign simple like the rear sway bar endlinks, when i got my car one of them was busted and would clunk around on left turns. 10 dollars to replace both if thats the case.

 

My buddy's Z is doing the same thing. He's got the 9" with I believe an auburn pro diff. It started out only clunking on right turns, and some whining after 25mph. Now it clunks and pops on all turns, and real bad in reverse. The whine has gotten worse as well. We assume it must be the differential, maybe bad clutches or something. The ring and pinion and all bearings were replaced so it's really the only thing left. Sounds a lot like your problem. The sound could be echoing off of your driveshaft giving the illusion it's coming from up front. Either way, a whine is never a good thing in my opinion. And now my da#$ car is doing it!!

 

ahhh phew.... it was simply my DS loop hitting the bottom of the floor pan. easy fix

I put sythentic gear oil in the dif as well and that quieted it up somewhat. it sounded way worse with the DS loop touching the floorboards though... every vibration in the drivetrain was felt!