Z28 thermostat housing

[montgomg]

I have an original  thermostat housing (PN 3877660) for my 69 Z28.
I understand these to be date coded but do not find a date code on mine. I do find a 9 followed by the letter P inside a diamond.
Could someone shed some light on this. Thanks.

[JohnZ]

660's aren't date-coded; those are mold cavity numbers and supplier identification.

[montgomg]

Thanks, I appreciate the info.