I have a set of heads...the castings under the valve covers are: 6f26 the other is 6f30 I guess those are just the date codes Both are also stamped WC P Thats all that I can see that is stamped on these things....I dont want to take them off to look underneath them- or am i going to have to? What heads are these? I have been researching and i just cnat find them.
I think you pretty much have to take them off. The date codes only tell you the year (within decade), month and day (of month). They don't tell the exact year. In your case, the heads could be 66, 76, 86, or even 96. The type of rocker arms on them might help narrow it down.