Hi Peter,
I kept the box with the part number on it for this exact reason and I thought it was at home. Unfortunately it must be at the airport with the maintenance log. I do remember I purchased it from
http://www.gaspares.com.au/ And I typed the Oregon 33-345 number in the cross reference part number section.
As Sod's law would have it the site seems to be down for some reason. I may get to the airport in the next few days if you can wait or I'd just try giving them a call. Think it was about $45.