Hi Sparky,
According to the R-25 performance data sheet, which you can download here or at the Ranger Tugs site, if the boat has the 150 Cummins this is the prop spec:
Propeller (17x15) (3 blade) (.105 cup) Acme #1384
The 130 Cummins uses 1" less pitch:
Propeller (17x14) (3 blade) (.105 cup) Acme #1386