2021 Mack GR64B

Duty cycle points to vocational rolloff work, 158,000 miles suggests steady in-town or regional cycles with frequent PTO time and stop and go loading. Serial 1M2GR3GC3MM021540, stock B3707P. Powertrain details are not provided, so verification should focus on engine hours, PTO engagement history, and ECM pull for fault codes, derate events, and regen frequency. Rolloff applications put extra load on cooling stack, driveline angles, and rear suspension, so those areas deserve a close look during inspection. Frame rails and rear section are the telltales on a hook truck, check for rail flaking, added holes, and stress around hoist mounts, crossmember ends, and any reinforcement plates. Hoist subframe and hook gear should be checked for pin and bushing play, cylinder rod pitting, hose chafe points, and valve bank seepage, along with smooth spool operation under load. Cab interior and controls should be evaluated for switch wear at PTO, hoist, and interlock functions, plus seat base play and pedal wear that can hint at actual duty intensity. Brake and tire wear patterns should be checked for alignment issues common to tight-turn vocational work, and driveline U-joints, carrier bearing, and slip yoke should be checked for looseness and fresh grease purge.