The Mekton miniatures line were based on the designs for RTG's long-defunt Mekton RPG circa 1994 or so. That being said, the Stallion is pretty obviously cloned from the Megazone 23 Garland; RTG were neither subtle nor reluctant to gratuitously steal art from other sources, modify it a bit and claim it as their own.
With that being said, I've never seen a full list of the Mekton minis line.