Wanted to remove my front axle in the next couple days but can't wait for ebay delivery delay.... went to Home Depot. In the nuts/bolts aisle they have a 5/8 hex coupling. It's just a couple bucks. Looks just like this
Works great. I just brought a 24mm wrench with me into the store for a test fit. It's maybe 1/2 or 1mm smaller but who cares. Fits in the hole.
Before I found that tip I went to Princess Auto and KMS Tools and neither had anything in a hex over 19mm.