Tapered Pipe Thread, including British Standard Pipe Thread
See: * Heater Hose 27070-H1000 CONNECTOR-WATER INLET [rear of cylinder head] $4.13 3/8 BSPT
* Oil Pressure Sender The oil pressure switch threads is 1/8 BSPT (british standard pipe tapered) * Flywheel 3/8" Flywheel bolts, early A12