Why do Rolex 34mm often have 1002 casebacks?

[cwebb3]

Sorry, New member here.
Tried searching but got too many other results to find my answer.

Why, with 34mm 5500 Air Kings or 1500 Date models, is the case back often stamped with 1002 instead of the same 5500 or 1500 as the case itself?

Does that mean that the back has been replaced during service (even if the case back date is similar to the serial # year). Or did they just install these at the factory depending on what was in the 34mm parts bin at the time of original assembly?

Just curious as I have one Air King 5500 with a 5500 back and another one with a 1002 back, yet both backs are stamped with the same year as the serial # year so I don't think it was a later service swap. I have seen this too during internet auctions where they show the movement and case back.

Thoughts?

Thanks
Charlie

[TimeToGo]

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One of those Rolex things... Installed at Factory.
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Plenty discussions on the forum with the same concerns.
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https://www.rolexforums.com/showthread.php?t=546251

[Dan S]

Rolex did frequently use case-backs from similar models, seemingly interchangeably although perhaps is was in an effort to use up excess stock.

[PVR]

Originally Posted by dan s

rolex did frequently use case-backs from similar models, seemingly interchangeably although perhaps is was in an effort to use up excess stock.

^^this