Jimmy Noel came to Hollywood in the 1940's, after a modest career as a bandleader. His rough looks didn't bode well for the big screen, but he found substantial work when many studios produced Westerns for television. One that he was generally in demand for was this series. Star Hugh O'Brian valued loyal background players (extras), and those who put the show ahead of other engagements had steady work. Noel was the most loyal of all; he had more appearances (over 150) on the show than anybody else except O'Brian. Extras back in that day made a flat daily fee, but it was adjusted upwards if the extra did more than stand around, such as stand in with the stars, speak, bow, or do much of anything. The more substantial the work, the better the day's pay. The generous O'Brian tried to spread additional work around his loyal core group of background players, including Noel, Ethan Laidlaw, Chet Brandenburg, Bill Coontz, Phil Shumaker, and Jack Tornek.
Unfortunately, Noel had very little acting ability, and his voice was on the rough side. Therefore, like Tornek (who was a decent actor, but who had a heavy Russian accent), any additional perks were generally on the non-speaking side or in minor stunts.
Here, he has a part more substantial than anything else he did on the series. His acting was wooden, and his voice sounded shaky, but both fit the character assignment he was given, and he ended up looking good. Such as it was, this was his moment in the sun.
When the producers of Gunsmoke were looking for a stand-in for the frail Milburn Stone (Doc), O'Brian recommended Noel, who was about the same height, build, and hair style as Stone, and who could do stunts when needed. Noel was signed on in 1960, and he worked with the series until it ended in 1974. To help pad his income, he was also given many bit parts and additional background work.