Very interesting article, thanks! I've been looking for a Jak-Lok for several years, but have yet to see one for sale. Even photos of one are hard to come by. Makes me think there weren't very many of them made.
I do have a couple Gear-Grip tools though. One has red grips, solid handles, and is marked with a NEFF logo and Pat. Pend. The other has a stamped steel handle and is marked HUNTER TOOLS and GEAR-GRIP and the patent number.