THAT was the voice of Isaac Hayes viewers heard on last night’s episode of “South Park” – even though the velvet-toned soul singer quit the show.

The makers of “South Park” used old audio clips of Hayes from previous years to cobble together dialogue on last night’s season debut, a Comedy Central spokesman confirmed.

Last night’s episode – called “The Return of Chef” – seemed to be set three years in the future. Chef has left the town of South Park to join an organization called the Super Adventure Club.

The story was about his sudden return to South Park.

The episode was rushed through production last week after Hayes quit the show to protest an episode that picked on actor Tom Cruise, a fellow Scientologist.

It was the latest salvo in a complicated and public war between “South Park” and the controversial Los Angeles church.

Hayes resigned from “South Park” more than four months after an episode – titled “Trapped in the Closet” – aired poking fun at Cruise, his sexuality and the modern faith that he adopted after going to Hollywood.

When it first debuted last November, Hayes reportedly laughed it off.

The resignation – which came in the form of a press release from Hayes’ publicist – set off a fight with “South Park” creators Trey Parker and Matt Stone.

Comedy Central quickly scheduled a repeat airing of the episode, but pulled it at the last minute.

Cruise reportedly threatened officials at Comedy Central’s parent corporation, Viacom, that he would refuse to promote his new movie, “Mission Impossible 3,” if the network aired the repeat.

The highly successful film series is produced by Paramount, a division of Viacom.

Reps for Cruise denied the allegations.