One problem related to mechanical jack has been reported for the 1999 GMC Sierra. The most recently reported issues are listed below.
I have a 1999 GMC serria and I had a flat for the first time I read all the instructions fillowed the safty like blocking tire / ect and that no good jack slipped off the axile and the truck fell on the ground , good thing I feep the kids away fron the truck , because I tought to my self that that jack was no good.