Hi there. I know this might not be considered vintage Heuer but I thought I could ask here. If not, please guide me to the right forum. So I have this lovely cs3110 with an odd caseback. It only says 'Heuer', no ref or serial number. Is the caseback wrong? Or were there a few released this way? (The casebacks I've seen online are all stamped with ref and serial numbers) Would love to hear any insight (maybe others with the same caseback). I do want to mention the watch is authentic and has been overhauled by one of the most reputable watchmakers in Israel. Thanks in advance!