The big rigs usually got used, abused, worn out, and scrapped after a few years of use. The big GMC engines like the 426, 503, and a few others of the same design actually had bolt-on cylinder assemblies that could be removed from the crankcase. After a few re-ring jobs and the cylinders getting taper worn, it was possible to bolt on a new cylinder bank instead of boring and buying new pistons. The big Diesels took the concept a step futher, and used cylinder sleeves that could be swapped instead of changing the whole cylinder assembly. Unfortunately, most of those well-engineered old engines got trashed along with the worn out trucks they powered!
Jerry
