The Drive Washer that is used on the ST C35 is the same as those used on all of the G21 series and the same as the ST V 51, 56, & 60. These are hard to find - but if you just want to fly - the current production Drive Washers as used on most of the Super Tigres - at least - up to the G51 will work perfectly. The part number is 22221058. You will also need the Collet - part number 22100234. These should be available at your LHS. If you can't find them I'll send you a set for $7 shipped. ----- Bob Jones