I have a couple of the Comet 350 seriese clutches. They use a 3"bell.
http://www.mfgsupply.com/gomini/gominiclutch/gominiclutchutility/gominiclutchcometla350/011135a.html
http://www.mfgsupply.com/gomini/gominiclutch/gominiclutchutility/gominiclutchcometla350/011135a.html