Re CAT Pumps for D60, and I am not sure which model we have on SM#396, (I assume either 237 or 277), but this is the tech info I have on-file on this matter, FWIW.

+++

On some units, the centre plunger is removed and the cylinder blocked off.  This is done in order to reduce the flow for water-making systems producing less than 160lph.  Check whether the model number is 237 or 277 - these models use the same seals and o-rings kits, with the Model 237 being a short-stroke 1725 RPM model, with same pressure output but lesser maximum flow rate than the 277.

237 Technical Specifications

Stroke:                                                 7.3 mm / 0.287" 

Max Flow                                 8.7lpm / 2.3gpm

Pressure Range:                      6.9–103bar  / 100–1500psi

Inlet Port Size:             1/2" NPT(F)

Discharge Port Size:    3/8" NPT(F)

Pump RPM:                             1725

Drive Type(s):               Belt, Clutch, Flexible Coupling and Bellhousing

Material:                                  Nickel Aluminum Bronze

277 Technical Specifications

Stroke:                                                 12.7 mm / 0.500"

Max Flow:                                13.2lpm / 3.5gpm

Pressure Range:                      6.9–103bar  / 100–1500psi

Inlet Port Size:                         1/2” NPT(F)

Discharge Port Size:    3/8” NPT(F)

Pump RPM:                             1420

Drive Type(s):               Belt, Clutch, Flexible Coupling and Bellhousing

Material:                                  Nickel Aluminum Bronze

+++

David

SM#396, Perigee

Bay if Islands, NZ