Yes, I've heard of it. In fact, there is s small write up in Fred Crismon's book "US Military Wheeled Vehicles".There are only two pics in the book, one being of the engine. The vehicle was tested in 1963 by the US Army but not adopted. It had a 6-Cylinder Corvair engine; Yes. The same Corvair highlighted by Ralph Nader in his book "Unsafe at Any Speed".
As far as I know, there are no kits of this beast, although you never know about some little known resin company doing one.