Several years ago I addressed the question as to the differences between vane pumps and gear pumps with Reverso. If my memory is correct: Vane pumps- smaller, less expensive, higher flow rate, but you have to replace the impeller periodically. It is important to purchase the impeller from Reverso as the stiffness of their impellers differ from that used in water pumps. Reasonable lifespan of an impeller in a recreational boat is around 12 oil changes, though this varies depending on many factors- oil cleanliness, cold vs hot oil & viscosity being the major factors. Gear pumps- larger, more expensive, slower flow rate, but no parts need to be replaced except for an O-ring after years of service. Reverso is still in business so they can be contacted to find out if my memory is as good as I'd like to think it is! *RUDY & JILL SECHEZ* *BRINEY BUG-a 34' Sail-Assisted Trawler * *850-832-7748* Sanford FL TRAWLER TRAINING and ANCHORING CONSULTANTS ANCHORING-"A Ground Tackler's Apprentice"- E-Book or Hard Copy