Rick, thanks for your reply.
What about if there was simply a hole in the center of the beam someone could use a bolt and nut to make it fit various jacks. I'm not a fabricator or a welder. I also don't know of anyone who could make it for me. I'm interested in buying one... ready to use.
Maybe if there's enough interest here someone could make a few and sell them. Anyone else interested in buying a floor jack cross beam for their GT40 or Cobra?