340 X-Heads

[bradster340]

I have two sets of 340 X-heads: 1 set, that are on the freshly rebuilt 1969 340, has the X next to the #1 plug and the other set has an X on the underside. This set came off of my blown 340 stamped as a November 72. My Cuda is a 1973 model. I am wondering if there are any particular or noteworthy differences. The heads with the X on the underside have been ported. These are away getting inspected and repaired if necessary so I can't provide much more info.