Hello. I've spent a bit of time today looking at the parts manuals for the wr450 and yz450 and I've worked out that the 2006-2009 yz450 all have the same transmission parts and the 2008-2012 wr450 all have the same transmission parts. The parts manuals also show the 2007 yz450 & wr450 have the same transmission parts which I find hard to believe. I was looking at UK manuals where specific and Europe where not on the Fowlers website here in the uk. My question is, if I'm going to order 4th and 5th wheel and pinion gears from a wr450 to fit my YZ to give a wider spread of ratios, am I to order 2008-2012 gears? Thanks for any help.