This tool works on Generation 3 engines. If you're working on a Generation IV & V V8 engine you'll need GM-47971 instead.

C/K The only access hole for pressure checks on the LSI engine are at the oil galley plugs or oil pressure sending unit. The M16x1.5 thread in not common size for oil pressure gauge adapters. GM-42907 is only required to properly diagnose oil pressure at the sending unit port.