There is a guy on Ebay that makes crash mushrooms and the like seems to be able to make things to spec - might be worth dropping him a line:
here is one of his ads...
http://cgi.ebay.co.uk/YAMAHA-TRX-850... QcmdZViewItem Ohhhh...he has his own website now:
http://www.engineeringsolutionz.com/ Contact him direct then
Cheers - Frank