The bigger flywheels for 10.5 & 11 inch clutches are a dime a dozen, market is flooded with cheap Chinese repros & there are still a number of US companies that still make them. The small 122 tooth flywheel is virtually nonexistant. According to my parts books the last listing for the ring gear was 1967. See this Wilcap link- http://www.wilcap.com/webdoc4.htm