I asked this same question about this time last year post #259083, sorry I don't know how to get that link up. Dr. Drivability told me they are called well nuts, and I could buy some at The Home Depot. Sure enough my wife brought some home the next day with the matching bolts. Worked great just don't tighten too much. Buy a few extra in case you do.
Did you find the rubber dealies at Home Depot too? Mine are wasted after 30 plus years.
