In 1956, Franz appeared on a first-season episode of "Gunsmoke" titled "Indian Scout", performing in the role of Amos Cartwight, a scout for the United States cavalry who knowingly leads the troopers into an ambush by a Comanche war party. That same year he guest-starred with Joan Fontaine in the episode "The De Santre Story" of the NBC anthology series "The Joseph Cotten Show". Later, In 1958, Franz was cast in the second season of "Zorro", playing the role of Señor Gregorio Verdugo. He guest-starred as Jules Silberg in the 1960 episode "The Test" of CBS's anthology series "The DuPont Show with June Allyson".