Breitling Unitime 1765's have very rough engraving to case backs/inside case backs and sometimes different case backs with "waterproof"(copilot-like)rather than "water resistant"....also no serial numbers................any views on these discrepancies.I have a Unitime with Copilot-like case back engraved "1765 Unitime" but no 127xxx serial number-all original dial/hands etc.............bezel insert also has differing "triangle to top(some as surface triangle, some as indented).......were there different versions of this iconic model?

pictures, please ?

Breitling Unitime 1765's have very rough engraving to case backs/inside case backs and sometimes different case backs with "waterproof"(copilot-like)rather than "water resistant"....also no serial numbers................any views on these discrepancies.I have a Unitime with Copilot-like case back engraved "1765 Unitime" but no 127xxx serial number-all original dial/hands etc.............bezel insert also has differing "triangle to top(some as surface triangle, some as indented).......were there different versions of this iconic model?