What color should I paint spare track links?
That depends on the vehicle. “Normal” practice is to paint them as you would regular tracks with perhaps an extra touch of rusting since they are static and not in use. However, depending on the vehicle and the circumstances, it was not uncommon for crews to weld spare tracks for added protection and then paint right over them to include the camo pattern. If the spare links were meant as truly spares, then I would recommend not painting them in this way. HTH.