Front edge of pivot to door opening on my Wescott = 2 1/2". Top post to top post, center to center = 45 1/2". I'm****uming you're talking about the transverse measurement of the windshield posts where the top header cast piece slides on. Unless you're making your own oak header bow - the over the windshield piece - that top post measurement should come out somewhat automatically cuz the header bows are routed for the cast steel piece and once they're together where it is, is where it is....