RHYTHM & BLUES IN NEW ORLEANS, by John Broven, 1974, says:

What wasn't known at the time was that Huey Smith had recorded
his own song with Gerri Hall and himself taking the vocals.
"It was one of the heavier sounds Huey came up with," said
Rebennack, but Vincent had simply taken off the vocal track,
left the tremendous rhythmic backing track and had overdubbed
Frankie's vocal.

Frankie (quoted) says it was Bobby Marchan, initially.
RHYTHM & BLUES IN NEW ORLEANS book is even credited as source info in CD booklet!!

Best,
John