It was the model CVR-4000, originally released in 1962. Later, it became the XL-4000 and was sold up until about 1970. These vacuums were actually made for Oreck by a company called MacDonald electric in West Germany. Here's an example of one I just found on eBay:
Karl, I ended up bidding on that oreck you pointed out on E-bay. With 2 seconds to go I got sniped. That's ok... I'm sure something just as exciting will come along soon enough!