This has a 1/2″ UNF internal thread and 3/8″ UNF external thread. Examples of pump part numbers.
Lucas CAV DPA and DPS main driveshaft nut 7182-189
Lucas,CAV DPA Top Cover Stud,Bolt,DPA Governor Cover Stud
Lucas,CAV DPA top cover bleed screw ,CAV Diesel Pump Top Cover Bleed Screw
Lucas,CAV DPA bleed screw ,CAV Diesel Pump
Delphi 7123-388 Transfer Pump Blades Automotive Part For Lucas CAV DPA DPS DPC
Injection Fuel Pump Lucas CAV Land Rover 2.3 2 & 3 series DPA 3248F750