Chuck was correct, the '72 German Olympic team did use them.
Hugo Rickert, Dortmund, Germany, Rickert Bicycles, a KoF kinda guy, was importing Campagnolo gruppos and components directly. At the time Campy didn't need such monstrous quantity orders and a "small" builder could swing direct orders.
Hugo came up with the idea '71 - ish and asked Campy to build them for him. Campy wanted him to get 500pr. but relented and agreed to 300pr. first run.
At the time I was the only shop Rickert did business with outside of Germany and we received the first Campy HI-Lo's in the country with our Rickert bicycles sometime in '71 to '72. The hubs proved quite popular, being used by the German Team and were then made and sold extensively. They had a good following in the U.S. and were sold by several distributors.
Subsequently, Phil and several others followed suit and made them for several years.
Hope this helps the Campy Timeline and any CR member that was curious about the origen of the HI-LO hubs.
Ted Ernst
Palos Verdes Estates, CA