'O', BTW, some very early '68 "X" heads (2531894) weren't even cast with an 'X', but to alleviate assembly line confusion, Chrysler later had them tooled to be cast with an 'X'.
Thats exactly how mine are. My car is an early 68. X-heads without the X. This can cause problems sometimes People will ask what heads I have... I will tell them they are the original heads. Then they will tell me how wrong I am and how a 68 340 should have X heads......
