Here is a photo of my Sekai 1000 - serial # Y1N1659 I was the original owner but sold it after getting a whiplash from a rear-end type car accident. I found it sitting alongside the road a few blocks from my house - it had A "FREE" sign on it so I picked it up not realizing it was "My" old bike. When I was cleaning it up I found the MN I.D. program number engraved on the bottom of the frame was in my handwriting and was my I.D. number. I took it to my favorite bike shop and had it overhauled - It looks pretty good for something that is at least 30 years old! Can anybody tell me what info is in this serial number? I think I bought this bike sometime around 1975 but can't be sure and I am curious. Thanks in advance for any info! 8-)