Power Train Driveline problems of the 2003 Chevrolet K1500

Drivetrain noise; ranging from clunk to metallic clank; problem has existed since new. 1-2 upshift causes clunk at driver side front. (4 wheel drive model) and clank iat differential. Situations with very light throttle (1-2 shift) result at times with impact/clank (w/ very audible metallic sound);sufficient to "shudder" vehicle. Shifting in 4w low (manufcturer instructions) also results in clank/shudder; not unlike being struck by a hammer. Slowing down/relasing throttle to negotiate 90 deg. Turns; throttle goes "dead" - no response - then responds abruply. On 2 occasions now-wet conditions-rear end (3. 73 limited slip), this has resulted in rear end drifting. My concern is snow/ice conditions. I view this as a legitimate saftey issue. Dealer has looked at this 3 times and found nothing wrong; claiming all functions are normal. The last time I had it serviced, their report noted that the symptoms could not duplicated; yet the odometer reading indicated less than . 2 miles driven. Rockenbach Chevrolet in grayslake illinois. They suggested that I get a lawyer.