Mike, I looked at the casting numbers again and it sure seems to be an 8, especially compared to the clear 6 on the other head. However, it could have just been a sloppy number. The two heads are identical as far as I can tell.

I don't know if the heads were ever rebuilt, but I am guessing not. They seem to have the factory hardware still.

I have pictures of the casting numbers and the entire heads and will email them to you if you'd like. Each picture is about a half meg though (very big and good detail), so I'd want the go ahead from you before I email them.

Thanks for the interest and let me know if you'd like to see pictures, etc.
-Chris