Sears Craftsman 9-29039 package of (10) 5/8"-1/2" round adapter bushings ($4).
ACE Hardware 20187 5/8"-1/2" round adapter bushings.
Vermont American 27974 package of (5) 5/8"-1/2" round adapter bushings.
Vermont American 27978 package of (5) 1"-5/8" round adapter bushings.