I got a different head for my pv engine. My original head was from a 1999 xl1200ltd. It used two 10mm bolts on the end of the head near the pv cables. The new head has the area for the bolts but its not drilled and tapped. I noticed they changed the part numbers frequently on these. I know it doesnt matter but Im a curious person and wonder why they made the change and whether I should drill mine or leave as is. I love knowledge and was wondering which was the better design. The later models show these bolts being none existent where mine show them being there. Hopefully some of use can learn something new!