Carter 3497 71-75 Freshwater 361/440 Marine and Industrial pump. Did you get that one off ebay? I was going to buy one to open it up, but they sold out. Take it apart and tell me the internal casting marks in the middle section and bottom. The Top has the hemi casting. That serial number after the 3497 is a much later 2000 date code serial data. Would be a good BB pump, and depending on the internal configuration and spring, may be Hemi type, or just a normal pump like the 6903. But considering marine use may very well have a higher volume per stroke.