I'm coming to the end of the road on this issue , please bear with me. I rebuilt a Holley 4175 using a kit I bought on E-Bay. I've been having needle and seat issues . The fellow from Mike's Carburetor wants the number off the air horn before he sells me a needle and seat kit . I'm wondering if these needle and seat kits are specifically matched to the number on the air horn? I thought all I needed was the model number (4175 in this case) and then it was a generic needle and seat. Anyone? Paul