Small block head

Where do you find the markings to find out if they are j /x heads ? pic would be helpful . Thanks in advance

i think there is a cast X or J under the valve cover, somewhere close to the head casting number.

Those letters are cast into the head by the spark plugs, #7 on the drivers side and #2 on the other side, the head casting number is cast on them near the 2nd rocker arm stands
BTW the 1970 to 1973 340/360 915 heads came in two different valve sizes as well as several different letters cast on them not just the J

thanks for correcting me cab !
it's been a LONG time since i played with a small block. if i remember correctly, it was around 1983 or so.

The photobucket watermark is exactly where I don't want it for the J head, but there's enough there to see where they are..

i uncovered the only small block i have just to see, and yep, a big fat J was where it was shown in the pics.
now if i can just remember !
1983 till now. 26 years. wow.

1983 is 36 years ago.

see, i can't count either !
CRS and "oldtimers" disease are serious medical conditions !

You are better off looking for the casting numbers for J heads.

The 1970 up 915 heads can be J, O, U or Z.

Around 1974 or so, another J head came on the scene, it is a 974 casting.