Hi Dave,
I was wondering whether you were looking for the mudguard that hangs down off the back of the airbox? And keeps mud off the rear shock...
I think this one is the same between '04 and '06 - and I have used one off of a KX250 in the past - but that was long ago for my 2001 ec300.
Or are you referring to the enduro fender extension that comes off the main rear fender?
jeff