Need help on reference 16800 with possible service case (4-million)

[Bladeshot]

Hi. New in the forum here and looking for guidance. I recently purchased a 16800 which has a 16800 case back and the case with serial number 4401449. Was told that this case could be a service case used as a result of damage to the original, and that might explain the mid-70's 4-million serial on the 16800 piece. Complicating the "explanation" is that the previous owner enjoyed the piece as a two tone for many years. I would like to take this back to reference, and wondering how the serial number could be accounted for. My friend suggested I ask here, since there is such a deep knowledge base.

Guidance and suggestions appreciated. Thank you.

http://s1073.photobucket.com/user/bl...erial%20number