Hey Scott,
After extensive digging and looking at the other models on that page as well, I am going to say that this is not a kit, but a well done conversion. It pulls in elements from several models that tamiya made. It could also be one of the lesser known brands, but since Tamiya was generally working in this scale that's what I'm concluding. If it was a kit it would have had to have been made after 1984.
chris