Thats a good Question. I'm used to customers coming in the shop and wanting the same replaced or remaned .I would if you have them, parts for the bike that is off the 2007. anything the 07/comes with you will need. top air box cover, possible inner air plate may need some changing or (not sure) you could use the one off your orignal bike. the complete wiring harness,the manual for the 2004/and the 07 should be compared on these kind of change overs.This way you can compare and work it out.Keep all parts from both, till you are up and Running for at least 5,000.miles. I would change a lot of gaskets too.I know the XB 9s & 12r really good. And the older Buells. Once in a while I'll get a lighting/model in. Hey! that 04 i would save for later. Have fun with that and post up the change if you can. [up]