I'm almost always amazed in the first few minutes of these shows (and others of the period) when I immediately spot familiar faces of actors. However, I can't tell you their names, and I doubt you would be able to do so, either. They were "no name" actors but you saw them frequently and they were excellent actors.
An example here, Philip Pine, whom we see in the opening scene breaking out of a Mexican jail with Steve McQueen. "Josh Randall" (McQueen) had gone undercover to help break out "Tom Dunn" (Pine), hoping the latter could lead him to recover stolen bank money. Everyone is in on the deal, the government and the warden of the jail. They have a concern: what is one member of the gang finds out this was all planned? What will happen to Randall?
The "breakout" scene, by the way, was very reminiscent of the something you'd see in the 1963 film "The Great Escape" as Pine and McQueen are seen in the middle of underground tunnels digging for safety.
Randall and Dunn ride to Dunn's ranch, and the two of them and Dunn's wife, played by Mona Freeman (a "known" actress), head out a three-day journey to find the money. Further problems arise when Dunn's illness is looking serious, plus he doesn't trust Randall. However, he's not a bad guy as just wants to give all the money to his wife, anyway. She tries to "moralize" him along the way. She doesn't want stolen money and these old western TV shows always had strong moral messages. I have no problem with that, but the story bogs down a bit because of the wife lecturing her husband a few times - in a nice way.
Speaking of morality, just when she's convinced him to do the right thing, however, real problems arise when the "good guys" don't turn out to be so good. I guess there are very few, if any, truly good people on this planet....except maybe "Josh Randall," of course.