Sounds like a chorus and a little eq scoop on the left side rhythm guitar, and a pretty straight forward distortion and slide on the first lead (right side) with just a very very tiny amount of reverb and slapback toward the end of the song played without the slide.
One of my favorite guitarists! I recall hearing somewhere that he uses a peso coin instead of a pick. He gets more than 4 for a buck!
Found this link here to his gear and effects, past and present.Lavon Chappell wrote:Billy Gibbons used an expandora disortion stomp box.But as they say tone is in the hands
"Bixonic Expandora - Billy would use six of these with different settings."
Clete