Cast Iron water outlet housing 3705018

[opelitis1]

Just came across this cast iron water outlet housing raised-numbered 3705018 - heavy l'il beast it is..
On the other side of the housing opposite the above number is punched  number 2 over GM.
Over the casting number is a square with something in it.. Very hard to de-cipher..
Possibly an early Vette thermostat housing..  Googled number but it seems a mite "murky"!!
Thanks!!
T.

[bertfam]

1955 (Exc A/C) through 1962 (possibly 1963), all V8.

Ed

[opelitis1]

Thanks!!
T.