Ed,

I couldn't find a full original pic of a Chevy C60, but did find some reference pics that the badge on the truck in your pic falls into the 1973-79 range.

I did find a pic (from an original brochure) of a 1976 GMC LCF which used the virtually identical body style (see attached below).

Based on this info, a good guess would put this as a 1976 (or right about then) model C60.

Hope that's helpful?

Dan
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1976-GMC-Medium-Heavy-Duty-CN.png (916.66 KB, 54 downloads)
1976 GMC LCF

~ Dan
1951 Chevy 3 window 3100
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