Chevy Chevrolet thermostat housing water neck GM date coded?
 

Did Chevy cast code the thermostat housings? I see some on ebay that have a 1 above the part number, meaning 1971? Saw another that had a 2 above the cast part number, again were these date coded?

I would guess that's more likely a mold (or "Cavity") number. Hard to get much out of a single digit date code, so hard to imagine they would have gone to the trouble for that.

^ I concur, I've never heard that these housings were dated either... and agree that it's not likely either. Cheers.