Looking to identify what these heads came from. The numbers on them are as follows: 3931063 GM4T
Also has PASS on them.
Mechanic describes them as a "semi-closed" chamber head.

Any ideas?

Yeah,
Semi closed chamber 396 heads. late 60's like 68'ish. Very similar to a 215 casting. Semi-closed chamber, probably around 105cc chambers.

Good head for a flattop 454 street motor.

From Mortec ( http://www.mortec.com/bbc.htm ) I got the follwoing information: 3931063....68-69...oval..CLOSED..396, 402, 427, 101cc chamber

Thanks guys:) Mechanic has a pair that he wants me to sell online for him eventually and we wanted to have the correct info on them.

I appreciate it:cool: