The red-anodised 'stabilisation' rods turn up occasionally. They screw into the top of the standard uprights once you've removed the black keeper. The thread and diameter of the rods are standard metric sizes, so replacements would be easy to make.

Not sure of the stabiilty, but the Norma manuals show it in use.

Much harder to find are the adjustable clamps. These also screw into the top of the standard, and then allow the red rods to be used as stiffening struts, linking the tops of the front and rear standards.