Ok folks here is my dilemma. I recently was given a Schwinn Le Tour. Here is the Thread. I am having trouble pinning down the month and year of manufacture. The serial number I have is 4I00xxx. The number is located on the left rear drop out. The Head badge has no numbers stamped into it. The head tube also no numbers stamped same with bottom bracket. The only numbers stamped into the frame are on the rear left drop out. Bike was made in Japan. Last night when I looked at the serial number I thought it was started with AF which would indicate January of 1970. Today under better light and with my glasses it is 4I and everywhere I look there is no reference to this serial number. The total number of didgets in the serial number is 7. Also there is no letter s to indicate it is a Le Tour. But all the components and badges are branded Le Tour. Any help is greatly appreciated.

Sites referenced to research serial number;

Re-Cycle.com

bunchobikes.com