entropicana, this might be of interest. Paraphrasing from CartoonBrew: "...Hanna-Barbera's oddest and rarest production: Rock Odyssey (1987). Produced in the wake of Ralph Bakshi's more adult animated features, when animation studios were attempting something a little darker, a little more edgier (think Watership Down, Rock & Rule even The Black Cauldron). The film was directed by Fritz the Cat animator Robert Taylor (though credited to Bill Hanna and Joe Barbera) and conceived to be a 'rock fantasia' of sorts. It was apparently cobbled together from disparate elements, bridged with a cosmic jukebox voiced by Scatman Crothers. The final result is a mess, but it has some incredible animation, layouts and design work."

Video clip here, artwork here.