No other parts are needed, just the two plastic halves of the handle, that said take great care when parting them as there is a spring inside that attaches to your throttle (yellow trigger) and could/will come out. Also ensure the pliasic lug that locates in the shaft goes in correctly, I did this to mine and it lasted for a whole single use. I ended up drilling two holes and putting in two small self tapping screws to hold the shaft and grip in place, it has worked very well and they no longer rotate. I hope this helps.
hemiuk
August 2010