I have recently bought this vintage IWC watch with Cal. 853 movement from an online seller. The serial numbers on the movement (1,486,xxx) and on the case (1,489,xxx) indicate that it was made around 1959-1960. Could anyone please help identifying the reference number of this watch? It looks a bit like 603A but not quite identical. There is no ref. shown on the backside of the case lid like in later IWC models. Can it even be a 'frankenwatch' assembled from different refs?
Would be very grateful for any hints or ideas.
