I use a 7/8" impact socket- 6 point. I think it translates to a 22mm in metric. I don't find there to be much slop in the socket, but a 21mm may fit. This wasn't much help was it?
22mm is the size socket you need 21 and 23 work but you will mess up the lugs that applies to 1500 and 2500 avs. the stud size is 14mm. hoope that helps L8tr