You're right, Hobie. The kid is Jason Lively, and he returned to Hazzard as Rod Moffet in "The Boar's Nest Bears". Two years after that, he played Chevy Chase's son in "National Lampoon's European Vacation".
Technically, Ernie Lively is Jason's stepfather. He was also in "One Armed Bandits", as Dobro Doolan. The part you're referring to is Longstreet B. Davenport, who showed up for three episodes in the second season. His final appearance was as Clyde, the Guard in "The Ransom of Hazzard County". NB. Ernie's first four appearances were credited as "Ernie W. Brown".