deepens. This model has acrylic crystal and sapphire display back. It has a serial number of 77061xxx. Around the outside of the back is Omega and symbol then the word "Speedmaster", followed by watch worn on the moon etc. So I think that the confusion lies with the seller because there is no documentation but came from a jeweler in mint condition with hang tag. We all know even ADs get their products mixed up. He is a longtime, well known, internet dealer in pre-owned watches. Now could the standard solid SS back be replaced with an Omega transparent back. Are they interchangeable? I don't know. The only source would be an Omega service center. As I said the watch should be in my hands Friday and should be able to find out more. Interesting. What does the case serial number say as to date of manufacture? I appreciate your time and efforts. Thanks
Ok then, we have solved the issue. The model should be a 3572.50 which is an acrylic crystal/sapphire back, caliber 1863. This model was discontinued by Omega several years ago but is available on the secondary market. 77061xxx should be early 2000 time frame I think the hang tag is wrong. If you indeed have a 3572.50 with 1863, you have a nice piece. The 1863 is "easy on the eyes".
As a side note, FYI, the standard casebacks are interchangeable with see through casebacks. The sapphire casebacks are available from sources other than Omega and several people have modified their 3570.50 with the see through case back. The only drawback of doing this is that the c.1861 was not meant to "show", so usually the delrin brake is usually modified with a metal brake for aesthetics.
