Originally Posted by
reluctantsuburb
Sorry, I missed this post. The head badge reads '1646'
Vintage Schwinn Serial Number Lookup @ BikeHistory.org.
From what
some write-ups indicate, out there, on the head badge numbers, the first three digits are the day of the year and the last digit is the year (which, in the case of a vintage Cimarron, would have to mean '6' = '1986').
Hope that helps.