I get a vibration or shudder after tranny shifts into 4th gear and only between 55-60 mph, replaced u-joints, front driveshaft, and motor mounts but still does it. what else could cause that
well my father is an experienced mechanic, and by the looks of it your gears might be slipping.. its an old truck and it might be time to replace your tranny or have a mechanic look at it.
Search GMC Sierra 2500 Questions
GMC Sierra 2500 Experts