HM, thinking of using 73 750 carbs on one of the 550's. Did I read somewhere that you can use stock 650 rubber connectors to attach those carbs to the 500/550 manifolds? Also , I was once warned that the carbs may not work because the slides in open position will interfere with the bottom of the tank, have you encountered this problem? I haven't tried it out yet because of the connector issue so I don't know for sure, but I'd like to know that it actually works before investing in connectors,so, does it work?