Believe you may be referring to the aluminum clamps for the G-series. Richard's has them. They work just fine assuming you have the hardware (shoulder bolts washers, and lock nuts) along with a battery with the side clamp locations.
Also, cut yourself a piece of Craftsman toolchest drawer liner to place under your battery, poking holes for your shoulder bolts. Its cheap, non-skid material
that offer some degree of protection from acid.
Comment on those aluminum brackets, I was rather surprised recently when I had an old set which were fairly rusted (might have been from the hardware mostly) on a recent tractor I acquired. Thought I might get a new set, but after a little steel wool, they were good as new.