72 Demon 340 J or X heads??

There are some misconceptions concerning LA heads.

1st- X heads are not "915" castings like J heads are. The casting # for X heads is 2531894 or in terms we generally use they are "894" castings. I'll be glad to pop a valve cover on my X heads and photograph the casting # if anybody needs proof. It also shows the casting numbers in the Mopar Perf. small block "A" engines book part # P4876826

2nd- As far as an "O" head being a J head with 2 J's stamped upside down from each other to make an O, that's impossible. Why? Because the letter is not actually stamped onto the head but was a part of the sand casting mold.