[JackG]

I modified four jackstands just for this reason. I welded about a 3"x3" flat plate to the top, then a 1-1/2" piece of pipe to that. Picture the top of the jackstand as a flat plate with a small piece of pipe sticking up that "plugs" into the jack point. The top of the plate is padded with a piece of rubber conveyor belt material. Safe, stable, and it can't slip. Too bad I don't have anything to put on top of them anymore!