I'm wondering if there is a big difference between the RCA 77DX and the RCA 77D. My understanding is the DX has a bit higher output. What can y'all tell me about the differences in the two models? Is the DX worth the extra money? Thanks!

They have write-ups for several RCA 77 variants here.
https://coutant.org/contents.html#rca
Haven't read through them myself so not sure if the answers you seek are there, but a separate write-up for each looks promising. coutant.org is a great source for ye olde mic info.

Langtry wrote: Wed Aug 24, 2022 2:50 pm I'm wondering if there is a big difference between the RCA 77DX and the RCA 77D. My understanding is the DX has a bit higher output. What can y'all tell me about the differences in the two models? Is the DX worth the extra money? Thanks!

No, its not really worth the extra money, even though the dude selling it will tell you it is.
It's liike 4dB or something?
If your studio is wired correctly, it should be loud enough to hit the preamp and have enough output so noise isn't a problem,

Thanks for both replies, that helps!