Drivetrain Issues You Wont Believe This!!!

9 DRIVESHAFTS NINE!!!!!... one rear end.. and one 4l60e tranny!!! I have a factory warrenty and extended warrenty they keep replacing the parts they installed a shim kit the TRANSMISSION WENT OUT last week its at the gmc dealer right now being fixed im done taking it there i need diagnois a fix it myself any suggestions ANYTHING PLEASE HELP THANKS!!

Take it to another dealer.
Don't work on it yourself unless you're sure it won't mess up your warranty.