Not prewar, but I have a few of these. And once briefly had about twice as many. (Traded for them, then quickly traded half for the same card I'd traded away) Maybe 12/24?
Other than one listed in the auction of the dealer I traded them to I haven't seen any of them again. Or any others.
And not baseball, but some t49s were unknown until I found some. Ended up with a complete set of cards that didn't have a completely known checklist at the time.
And a fun one, in 74, there was uncertainty who would be the As manager. There was a rumor that Topps made a manager card with a big question mark where the managers picture should be. (Not entirely implausible to a 10 year old especially with the washington natl league cards out there. )
I've never seen anything even suggesting it was even a proof since then, and now figure it's just one of those local rumors. But I still have a tiny bit of hope.... Maybe as a custom card someday.