the clunk is coming from the rear-end, every 8.8 rear i have ever owned has made the same clunk, the 2 piece shaft has very little play in it.
lift the car and hold the pinion, the stock DS is very solid
My thoughts exactly. I have yet to see any facts showing it from driveshaft and never will.
How does stock driveshaft causes clunk only on certain shifts. Because it won't "IF" it was the cause it would be in every gear. Amazing my 99 GT both 04 mach1 would clunk too that clunk noise from backlash in drivetrain. Most of clunk noise can be controlled by way you drive it.
Again Alum driveshaft will dampen noise because alum material works great as a damper.