The watch has been buffed hard and very badly oxidized in the past then cleaned. The rusted area will compromise sealing the watch properly.
Sorry to say it but this is quite the confection. 166 is a non chronometer code, and so the dial should not have 'Chronometer' on it. I suspect that on the train bridge decal it would show a cal 1022. The dial is refinished and it probably is not a Connie It has a Bombay "special" quality to it
I'm talking about the dial. 166.0261 is not in the database and I suspect the model is a 366 model (often the case back number was different to the model number). Usually the dials of these 166/366 models had "Constellation" and "automatic" below the Omega symbol. Sp I'm not saying the case back isn't a Constellation case back, but that something odd has happened to the dial.
Yes, but this doesn't look much like a faked case (because of the heavy polishing) so I'd assume the caseback came from a 'real' Constellation. And it seems too odd to think they went to the trouble of polishing the inside caseback and then stamped it with the wrong number.