Drivetrain noise

[mag0093]

I replaced my clutch with the ACT street kit. Everything else with the drivetrain and engine are stock. About nine months after the install i began hearing a clunking noise The noise is like a fluttering one when i let off the throttle but it gradually disappears as the rpms go lower. I had it up on the lift today with the ebrake on and the driveshaft was able to shake back and forth plus make a noise that somewhat resembles what i hear when i'm driving. Any suggestions as to what this could be?

[SauN]

make sure all your nuts and bolts on the drive shaft to the differential are all tight

also check the differential fluid to see if it low or dirty.