1990 GM 1/2 ton, every 20K needed to replace the front axle seals on the diff, not a quick job. They had to drop the front diff each time. 1994 GM 3/4 with the 6.5 diesel, 7 injector pumps, oil cooler lines, transfer case seals, rear axle seals, rad hoses that had funky connectors, clutch that had the dual mass flywheel. Never another GM product.