X Head O Head Comparison

All 'O' heads are 2.02s, as they were a mid-1970 ONLY 340 production piece.

What is the difference between the 'X' and 'O' and the other 2.02 3418915 derivatives, you ask?
The lower row of head bolts have wider load bosses on the 'O', 'U', 'Z' and 'J' heads, that's all that's different.

Mark.