trying to find a clunking noise

ok ive been chasing down a clunking noise abut 2 months after i did my 12 bolt

symptoms: 1: very loud clunk/ bang when i nail the gas (any rpm any mph but not from a stop) sounds like its comming from the center or rear of car
2: clunking just when i go into O.D. in between 40- 50 but when i tap the brake while hitting the gas to get out of lock up, its gone. souds like its coming from the rear of the car

how long: the first symptom happend im guessing arond after i had my tranny built with a new 3200 stall converter.

the second symptom has been happening about 2 months after i had a moser 12 bolt installed before and after the trans was built ( i did the tranny after the 12 bolt)

what has been checked/ replaced: new poly trans mount, T/A mount, all bushings in rear to poly, new lakewood lca's, periodicly checking T/A mount on the 12 bolt, ls1 D/S w/ new u joints, new/ upgraded flexplate, exhaust is clearing everything too

what has NOT been checked/ replaced: motor mounts front end bushings shocks and springs, rear gears after or before install of 12 bolt


only thing i can think of is the backlash on the rear or slack on it but im not sure how to check it, its a moser 12 bolt 3:91 gears and a detroit true track diff 33 spline axles and upgraded 1350 series yoke

sorry for the long post but any help would be great

Check to make sure your driveshaft isn't too long....when the rear squats, it could be causing it to rub against the rear seal in the tranny.

update:

still getting the chatter but from doing reserch i think its the tcc. for some reason when i tap the brake in od it goes away, had my drive shaft shortened and its still the same, im also now getting the chatter at higher speeds (like 65- 75mph)but not as harsh. its harsh around 40 to 50mph to a point where its banging bad and shaking the whole car kind of like a broken mount, its more of a bad and violent chatter then clunking, also its not rpm related, my friend told me if i put the stock converter back in the car it may go away, but i was wondering if i can find this problem on a dyno with the pcm being programmed and checking all the sensors.

Please help i cant take it anymore, has anyone else had a problem like this with a 2800 or higher stall?

Thanks --frank--