Very similar to 1967 truck. Small back window is discontinued, so all 68's will have big back windows. Side marker lamps are added to front fenders and rear bedsides. Some CST equipped trucks have upper side trim in addition to the lower side trim. CST's also have bright trim surrounding front grill and headlamp area. Letters on GMC's are now moved from grill to front of hood. First year for the optional 307 ci. & 396 ci. engines.