For All early engines.
Aluminum body with bypass hose take off, this original type pump has a small cast metal impeller for early 850, 997 and 1275 Cooper "S" engines A series engines. Further reduction of cavitation is achieved by using a large diameter water pump pulley CAM6408 as originally fitted to the Cooper S and reintroduced on the A-Plus engines. It is necessary to check clearance between the large pulley and the head, if a lot of material has been machined from the head face it may foul the pulley.
Small bore engines with 12G940 heads can't use CAM6408 and it is necessary to modify the top edge of the high capacity water pump or the 12G940 head will rest on the pump and not seal properly, modify for at least 1/16" gap.
This original small cast impeller type pump did not churn water as much as the current later GWP134 large impellor pump.