No mystery, really. It should have a Westfield serial #, and 1936 started with A 5000. Each year started with the next letter, until the F series gave way to G in 1941, and ran through '44. Check out Mr Columbia's site, he used to work in the Westfield/columbia plant. Also, Classic Bicycle News has published two books about W/C bikes, one from the early 30s-41, and the second, 45-63. -Adam