It's interesting that it wasn't that band they mentioned. Rather, the Rolling Stone mobile recording truck. The Stones commissioned it, but it became so popular that it became a business used by many bands in the early 70s. Deep Purple was waiting their turn to use it when a fire started during the Zappa concert. It was caused by a fan with fireworks. Thus the storyline of Smoke. Btw DP used the truck to record Machine Head, Burn & Stormbringer