Bolt size/thread in Harbor Freight tire changer?

[Chiefy]

Has anyone figured out the size and thread of the bolt inside the Post cap on the HF tire changer?  And whatever size it is, would our Dragons wheels fit over it?  I saw where someone dropped a 3/4 in unthreaded rod in there.  But I'm cobbling together a home made MC adapter for it, and would prefer that the rod screws in.