There was someone making replacement poly cush drives, I never tried them
myself and Im sure someone will pop along shortly and let you know where to
start looking. It seems some XT's suffer more than others. My XT660Z used to
eat them. 500 miles from new and sprocket would have play. Stuffing strips of
tube into the wheel hub used to make them last for about 5k miles. Just to put it in
perspective I had never changed a set of cush drive rubbers on any bike ever until
I got the XT. I read a post somewhere that suggested the sprocket bearing could
be modded to make the cush drives last a bit longer. Guess if you search here you
will find.