In Dundee and the Culhane, Garrison joined John Mills as the junior partner of frontier lawyers taking clients in the American West. Garrison had relatively few acting roles thereafter, none long-lasting. In 1968, he was cast as Buck Hambleton in the episode "Ordeal" of The Name of the Game. In 1969, he played Samuel J. Coles in "A Reign of Guns" in The Mod Squad. In 1970, he was cast as George in "The Pied Piper of Rome" on the comedy To Rome with Love. In another 1970 appearance, he was cast in Love American Style. In 1971, he portrayed Harvey Bishop in "The 5th Victim", the twelfth episode of Alias Smith and Jones. His subsequent roles included Clint Carpenter in "Harvest of Death" (1972) on Mannix, Detective Robert Scott in "The Violent Homecoming" (1973) of Police Story, Lanark in "The Second Chance" (1977) of The Rockford Files, and Captain Buck Tanner in "PlayGirl/Smith's Valhalla (1980) of Fantasy Island.