Factory installed spark plugs 1969 BB with cast iron heads.

[daveg]

Diggin for info on 1968 turned this up.
Pics 1- 2 are GM info announcing the new "ACniter" plug,
Pic 3 shows the 'performance" plugs came along much later.
Pic 4 shows one of the sets of boxes dated 1969 BB cast head plugs I have.

Pic 5 shows a
set of 68- earlier BB cast head plugs. Boxes dated 62 and 63 so maybe 409???
set of 1969 BB cast head plugs. Boxes dated 1969.
set of 1969- newer BB cast head plugs dated 1973. Note difference in box.

This is all I have on this so enjoy or ignore.