The difference between each of the Diesel Engine Spares Kits is the parts included for the water pump and the lube oil filter (The 5411 uses a different oil filter). To identify which water pump you have, refer to the additional picture below.

Applicatioins include these engines (and the boats that we are aware used these engines... There could be other combinations as well):
• M-12 (Catalina 25, Capri 26)
• M-2-12 (Catalina 25)
• M-18 (Catalina 27, Catalina 30)
• M-25 (Catalina 30)
• M-25XP (Catalina 28, Catalina 30, Catalina 34, Catalina 36)
• M-320 (Catalina 27, Catalina 28, Catalina 30)
• M-35 (Catalina 34, Catalina 36, Catalina 38)

1) This pump may have been replaced with the late model Sherwood pump by a previous owner. Earlier Universal diesel engines of most any model could have the newer pump as Universal provides an upgrade kit to replace older Sherwood or Oberdorfer pumps that have worn out. Compare your pump to the drawing to ensure you are ordering the correct impeller kit. If your pump doesn't look like this drawing, see the pump below under "May we also suggest" for the late Sherwood replacement pump impeller.

2) In 2004 Oberdorfer changed the seal on the cover plate from a paper gasket to a reusable "O" ring. The o-ring included in this kit will not be used on a pump equipped with a paper gasket seal.

3) At about the same time as the gasket change, Oberdorfer changed another characteristic that will help you to determine if you have the paper gasket or the "O" ring before you open the pump. Order the proper parts in advance before you need them. In early pumps the cam inside which flexes the impeller vanes (and causes the pump to pump) was a separate piece. In later pumps the cam was machined as an integral part of the casting. The machine screw that secures the cam into the early pump is visible on the outside of the pump body, between the two ports. Since the later pumps don't have the separate cam, there is no machine screw visible. So, if you pump was built around 2004, check for the head of this machine screw. If it has the screw you likely have a paper gasket. If there is no machine screw you likely have the "O" ring seal.