Stan:
According to CBTN, both the LS-6 and the L-78 used the 291 ehads in 1970.
Here is what CBTN (65-69) says about the 2 sets of heads:
840
<UL TYPE=SQUARE>
* This cylinder head was the first big block head produced with a temperature sending unit boss. Very late 1967 cylinder heads would have the boss, but it would not be drilled and tapped. Production of this head began around May 1967 and ceased around May 1969. This head is identical with #3904391 except for the temperature sending unit boss and two accessory bolt holes added to the end of the head.[/list]
291
<UL TYPE=SQUARE>
* This cylinder head is indentical with #3919840 except that it has a tapered spark plug seat, and an exhaust valve seat redesigned to accept the 1.88 exhaust valve. As with #3964290, #3964291 was produced with both "N" and "peanut" series type spark plug seats. This was the last closed chamber square posrt cast iron head produced. It was produced in both plug designs for service replacement, including 1965 through 1969 model years. This was also used in 1970. [/list]
So, does Colvin mean the 291s were ONLY used as service replacements on '69 cars, or that some cars could have gotten them?