oooh interesting, did you find these on a site like archive.org?
Archive.org has some of it, but your best bet might be the Old Time Radio Researchers' website:
The only downside there is that their current version of the website is easily searchable but not easily browsable. So it's great to get stuff if you know what you're looking for, but you can't just thumb through a list of shows to decide on something to listen to.
Well, actually the second downside is that they seem to have removed the view option that makes things easily downloadable and now the way you have to do it is click the show name, then right-click the little player that pops up and select "Save audio as..." from there.
The other thing that might be an issue if you're sort of OCD about organization and such is that the mp3s are often crappily tagged so you might need a piece of software like MP3tag to edit things so that they properly display the right episode titles, "album" (series name) and so forth. I tend to spend more time doing that than downloading because I also end up making album art as well
You may be able to find some of this on spotify as well. Most shows are widely available since the shows are now public domain (with a few exceptions. The Shadow
should be public domain but the rights-holder (publishing house Conde Nast) tends to go after lots of places that host episodes of the series.
Fair warning though that since preservation wasn't a huge thing in the 30s and 40s lots of early shows are incomplete, with missing episodes or even incomplete segments of individual episodes. Thankfully most shows are not serialized so it's not a huge deal.
Other sites worth checking out for info/research/series decisions:
List of old-time radio programs - Wikipedia (might be a bit daunting to read since it's a list of wikipedia pages. But it is informative)
The 60 greatest old-time radio shows of the 20th century [sound recording] in SearchWorks catalog (a link to a Stanford database entry on a cassette tape collection of the 60 greatest OTR works according to Walter Cronkite. There's nothing for you to get from there, but the complete listing of shows is a good cross section of some of the more famous/high quality series out there)
Big List of Old Time Radio Detective Shows - The Great Detectives of Old Time Radio (all from a podcast specifically about OTR detective noir/dramas. Has a bit listing of series out there while linking to the guy's own podcast episodes talking about them. I've honestly never listened to the podcast but the list of series is nice)
You can also ask me for recommendations if you want as well. This post is probably getting too long for me to continue linking things and rambling about stuff that's not hockey