The Gun Track is the "ladder" part attached to the bottom plate of the Proton Wand. On close inspection of a hero thrower, there are 2 machined discs, usually referred to as Gun disks, attached the main pockets of the part, plus a piece of scrap metal acting as a shim beneath the V-Hook. On a stunt wand, this shim is replaced with a third disc. The S-Hook is attached to the Gun Track using the rear-most disc, inverted.
This broken GB1 stunt wand (above, right) offers a clear view of the Gun Track without any additional hardware attached.