Pic: Rich, your collection of Hubley Real Toy school buses brings back memories!
I had one of them which I found in The Hobby Corner, a tiny hobby store in Pittsfield Massachusetts in 1958 or so. I wanted several but the guy said it was his last one. I bought it. That was before we could find anything on the internet. What impressed me about the bus model was that it was, like yours, an authentic replica of GMC with a bus body by Superior. In those days there were a number of school bus body manufacturers, Blue Bird, Carpenter, Thomas, Wayne, Reo Safety Gillig, and others. Now there are only Blue Bird, Thomas, and ICC. When I went to Lenox School, the school had two Ford with Superior bodies, the rear end of one of them visible in this picture below. Thanks, Rich, for the trip down Memory Lane. You did a fantastic job modifying those buses.