That looks like the same piece that came on the original rc10gt. There was a nut supplied that was used to gauge where to cut the crankshaft with a rotary cut-off tool. You have to cut the crankshaft about 3-4 threads past flywheel so the adaptor will thread up to the flywheel. You may even need the old style clutch bell and bearings but not sure since I've never had or seen a rc10gt2 clutch assembly.