Wrangler Jane (Melody Patterson)
From IMDb: Apparently auditioned for "F Troop" (1965) on a lark. She was not quite 16, and kept her age from the producers. When she had secured the part, she told them her age. Their shock and consternation were ameliorated shortly thereafter by her maturity and professionalism.
LOL! I remember an interview she did on the radio (Howard Stern??). She said Forrest Tucker "showed interest in her", to put it diplomatically......