So i bought a blown up 2006 RMZ250 to come to find out it broke all four valves and one valve pushed halfway through the head and is permanently positioned there, piston is trashed, bent rod, and a few nicks in the cylinder. So to say the least, the head is trashed. So i found a head from an 04 but upon some research i found it has a different part number. Riddle me this, the 04 has the same internals as the 06 (the valves, guides, seals.... basically everything is the same part number) the 04 and the 06 share the same cylinder (I know this because i have both out in the garage and they are identical), and they also share the same piston. The only thing that is different is the bare head part number. So why in the world would an 04 not fit an 06?? I think im just going to buy the head anyway because its a good enough price as where i could just resell it if it doesnt fit and could make some money.