They correspond to the assembly 1 in the exploded view of the fresh water cooling system and includes the following components.
2) Pump housing
3) Flange
4) Bearing
5) Mechanical Seal Assembly
6) Impeller
7) Nipple
8) Paper Gasket

OEM Equipment for the following engine models (and the boats that we are aware used these engines... There could be other combinations as well):
• M-18 (Catalina 27, Catalina 30)
• M-25, M25XP (Catalina 28, Catalina 30, Catalina 34, & Catalina 36).

• Flange, item #3 diameter: 2-1/8"
• Flange fasteners, centerline diameter: ~1-5/8"
• Impeller, item #6, diameter, outside: diameter: 2-1/8"
• Barb, part of item #2, input, large: 1"
• Barb, item #7, output, small: 3/8"