The Stovebolt Site Forums The Parking Lot '60-'66 Trucks Date Stamped in Bed

I have a 1965 C20 with the original wood in the bed. There is a date (I assume it is a date) stamped in the wood near the cab that says "6 (I think) 31 65". Is this the date of manufacture of the truck? If not, what does it mean? I would appreciate anyone's input.