Kent-Moore Tools Kent-Moore J-21867-6 Adapter, Oil Pressure Gauge For General Motors. J-21867-6 allows the technician to measure the engine oil pressure with J-21867-A Oil Pressure Gauge kit under a variety of engine running conditions in order to determine the mechanical condition of the engine. J-21867-6 is threaded into the engine block in place of the oil pressure sending unit and adapter, and the oil pressure gauge from J-21867-A is then connected to J-21867-6. The engine can be started and the oil pressure monitored. Email for product availability.