I saw the Yello Mello Bus down at the La Quinta Inn off 20th street the other day on the way to Riverbend and so we stopped by to get a close look and some pictures. I have temporarily misplace my camera and will upload them when I find them, but for now I have found this picture of both buses.

Apparently they built them to help rebrand the marketing strategy for Mello Yello and there are two (supposedly a 66 and a 67- one is a bench seat, the other is walk-through). The Bench seat was at Riverbend and they said they will be selling both of them in September or October. They were pretty sharp, but the guy said they had trouble with it since it was 6v and the engine overheated. I told him that shouldn't be the case, but whatever... they were also running passenger tires... Good thing they were trailering it everywhere!
I'll try to get some better shots of it another time.