One problem related to automatic transmission column shift has been reported for the 1999 GMC Sierra. The most recently reported issues are listed below.
Went to dealership talk about techical service bulliten #86-74-03 clunk upon acceleration(replace transfer case fluid). Dealer changed transfer case fluid, but glunk noise is still there. The service bulletin states cause maybe to slip-stick condition between the rear propeller shaft slip yoke and the transfer case output shaft. The correction, drain the transfer case fluid and refill with fluid. This fluid contains a friction modifier thar should eliminate the slip-stick condtion. I feel that this service bulliten procedure did not correct the cluck problem. I said, to the technical manager that there is excess backlash between the crown-wheel and pinion in the diff. Pull it out and adjust it, as it will shorten the lfe of diff. He stated that there is no room to adjust it. I have a 1992 model that makes a clunk noise. I think my ujoints are being effected because of the backlash. I place my truck in drive then reverse I get a slight clunk feeling. Iam not a expert, but I don't think the TSB really corrects the clunk.