Hello Rusty
Thank you for posting all the links. I am, however sure that Allegro's serial numbers are sequential and logical.
I know Stefan and his wonderful page speedbicycles, but one of the bikes has a wrong date which causes confusion.

P.S.: Thank you for your PM, unfortunately I can't answer it at the moment as I got this info:
The administrator has restricted use of the private message system to members with less than 10 Posts
I will come back to you later.
Regards
Michael