1980's Riddell Helmet Shell Dating

[cohibasmoker]

Guys and Gals, I need a little help. If a 1980's era Riddell football helmet has C7 stamped into the shell, just below the ear-hole, would that date the shell manufacturer to March of 1987? I am not 100% sure so I figured I'd ask.

Thanx,

Jim

flaa1a@comcast.net