I've seen both, a not-too-cheap 3-tubes 531 rig with Campy Sport/Gransport and Weinmann 27" rims, and an all 531 which was identical to a Falcon top of the line San Remo bike. Harding's on Westwood Blvd. in West Los Angeles sold them ca. 1975. About seven years ago I saw an unridden high-end one at a store in Spokane, WA. Frame details--fork crown, seatstay plugs, finishing of the stay and fork blade ends--are visually very different from "real" Eddy Merckx frames. David Feldman
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> Falcon-made Eddy Merckx frames from the 1970s ... decent 531 frames? Or
> gaspipe?