Before teuck engine collapse. Ww had concerns about truck sounded off. Misfire in engine, knocking noise. Truck shut down. Had it towed. GMC service department concluded that the 5th cylinder not firing properly. Lifters collapse. Fixed, it was costly $10, 100. Truck went back in shop next day mexhanic was busy. Waiting til after weekend to take truck back in. They had to physicallt look at why truck was vibrating. Engine light not showing issue. Neither did the code reader. Mechanic found provle to be the Torque convertor. Need to change that. Said it was a very common problem in Chevy trucks.