I picked up pair of 243 heads and after I got home and inspected them more realized they were slightly different. To start the way 243 is cast into the head is different. And we're the coolant lines attatch to the heads on side has the hole cast over in the back and one side had both holes open. Possibly different year castings?

Thank you. That's what I thought but wasn't sure. I'll have the machine shop open the other whole up because I'm going to be using a coolant cross over kit.