I use the cb6 c ring and bridge piece with spacers taking up the free bit of the c ring shoulder as the bridge bit with guide pins is not used. The cb3000 cage fits perfectly and all guide pins are packed with spacers to give it rigidity. The 40 piece spacer kit and steel pin came from LMS4620@tiscali.co.uk who make them for all cb 2,3,4,6,9, and curve models. That solves the problems several of you have osted recently