As we have discussed here (for a full history of Aurora's Godzilla model kits, containing everything you need to know, see this comprehensive article at Sean Linkenback's Showcase Daikaiju!), Aurora produced a "Monsters of the Movies" series in 1975.
These kits were designed by the late, legendary Marvel artist Dave Cockrum. However, another of the designs he submitted was for a Godzilla (you can see a photo of the prototype, now in the hands of a private collector, at the aforementioned link). This went as far as being sculpted by Ray Meyers, but, for reasons unknown, never saw the light of day.
But then, a couple of years ago, as my Ebay seller wrote, "someone got a hold of [the] Aurora patterns...took the resin kit to make styrene plastic kits." My understanding is that a limited run of 100 were produced, and quietly sold online for a short time. It's my belief that the leftovers of this run are what has recently been sold off on Ebay.