Robert Donner uncredited apparance?
Mr Donner played Yancy Tucker on The Waltons and I think he appears in Damnation Alley as one of the mountain men that the main characters meet along the way. He was the one with the real long black hair and radiation sores. Odd thing is that he isn't listed among the cast here at the IMDB entry for Damnation Alley.
edit: strike that last part. Somehow I missed that he is listed, apparently as a man/guard so he may have actually played two parts depending on how you interpret the listing. Anyway it's quite a departure from his down home friendly character on the Waltons.