I've now reached the end of the surviving Superman episodes. I'm afraid the half-hour version of the series was kind of disappointing. As I mentioned, there's generally rather little of Superman in them, and the emphasis is more on mysteries and crime stories than action -- which is true of most of the series, but before, the stories were long enough to have room for a fair amount of action and heroics rather than just one or two brief bits. Also, several of the stories are truncated remakes of stories I've already heard. The half-hour series also trimmed down the supporting cast somewhat; Batman evidently ceased to be part of the show, and at least in the surviving season, Jimmy Olsen seems to be missing; there are a couple of stories in which the role I'd expect to go to Jimmy instead goes to Jackson Beck's squeaky-voiced character Beany Martin, Jimmy's replacement as the Daily Planet's head copyboy.
One interesting example of a remade story is the finale of the penultimate season, "Dead Men Tell No Tales." It's adapted from the 1948 serial "The Mystery of the Stolen Costume," in which a burglar in Clark's apartment discovered his spare Superman costume and Clark turned to Batman to help him retrieve it and preserve his secret. In that version, the burglar, intending to sell the secret to a gangster, was shot by the police and could only tell the gangster the location of the apartment building before he died, and the rest of the story was about the gangster using various strategies to determine which of the building's tenants was Superman and Clark and Batman using various ploys to counter them. In the half-hour version, Batman is replaced by Clark's detective friend Candy Myers, who doesn't know he's Superman, making their cooperation rather more awkward. The gangster gets the full address and he and his moll know Clark is Superman, and to protect his secret, Superman flies them to a remote mountain where he intends to hole them up until he can find a solution, whereupon they promptly try to escape and fall off a cliff. If that sounds familiar, it's because it was remade again as "The Stolen Costume" in the first season of the George Reeves TV series.
In fact, looking over an episode guide for the TV series, I see that several of its episodes were remakes of radio stories. I hadn't realized that. That's another reason to check out the show, either on DVD or when MeTV starts airing it next month (I gather).
Anyway, there's just one surviving episode of the final 1950-51 season, and it doesn't have a single familiar voice in it. In that season, Michael Fitzmaurice replaced Bud Collyer as Clark/Superman, Jack Grimes replaced Jackie Kelk as Jimmy Olsen, and Ross Martin replaced Jackson Beck as the narrator. Lois and Perry aren't in the surviving episode. I was interested to hear how Fitzmaurice did as Superman -- I've been aware of him as a footnote for decades, and wanted to find out once and for all -- and he really didn't amount to much. He had a generic, announcery voice, very different from Collyer's -- with the sort of mellow quality that Bing Crosby's voice had, but blander, and he sounded more like an announcer reciting lines than Collyer ever did (even though Collyer was also an announcer). And he didn't distinguish his Clark and Superman voices much at all. He's a footnote who deserves to be a footnote, and I don't regret that I won't be hearing any more of his episodes (particularly since so many episodes of this series were live reruns/remakes of earlier episodes; they even did "The Stolen Costume" again, according to the episode list on Wikipedia!). As for Grimes, he was decent, but sounded less like a teenager than Kelk, more like a grown man vaguely trying to sound youthful.
So that's the end of that, I guess. Now I'm not sure what I'll do now that I've gotten into the habit of listening to old radio episodes while I eat or wash dishes. Although there are a lot of other old radio shows out there on the Internet. Maybe I'll try The Green Hornet next, or Dimension X.