I have a Sharmeter with brass tag stamped 513 it is original & barn fresh. Jacks book states that a 513 has one hose and one dial while a 512 has two dials and two hoses. My 513 has two dials and openings on the side panels on both sides for visi guages hoses and hangers. I guess my question would be is my pump tagged incorrectly or is it a misprint in Jacks book?

Thank you
John