Toby Huss does the voices of Cotton Hill, Kahn Sr., and several other incidental characters. Among other things, he appeared on an episode of Seinfeld as the mysteriously attractive TV pitchman 'The Wiz'.

http://www.tv.pop-cult.com/king-of-the-hill.html

I'm the Wiz,Nobody Beats me,because I'm the Wiz! On Family Guy,Puddy is the voice of Joe Swanson. It doesn't sound like the Wiz,Kahn Sr. and Cotton don't sound like Toby.

I remember Hank and his friends talking about Seinfeld once. I believe it was in a 1st season episode.