Ok so I've been following up on ya'll's ideas and I wanted to share. Thank you so much for all the help!!
So based on what EDW shared (
http://database.ukulelecorner.co.uk/site/ukulelemakers/uvw-xyz/targdinner) it was distributed by a Chicago-based company Targ and Dinner under the Biltmore brand line. Targ and Dinner didn't actually manufacture it though - they were a distributor so their business model was to purchase instruments from the actual manufacturer, rebrand and then resell the instruments using their different brand names. There also seems to be another Biltmore line called Biltmore Herald, though I haven't figured out what that relationship is (if there is one?) yet.
I've found some 60's and 70's scans of Targ and Dinner catalogues online. Only one includes ukuleles, but no listing for this particular ukulele or even any Biltmores.
I think I was wrong about the nut and saddle being replaced - I'd just assumed since it was bright pink plastic that it must have been more recent than the rest of the ukulele, but digging into the Targ and Dinner lead brought me to 2 listings for ukulele's with similar pink plastic nuts and bridges.
--
https://www.fleamarketmusic.com/uke-yak/default.asp?Page=141 - search for a question asked by a Tim about half-way down the page (subject is Biltmore Concert).
The photo shows what looks like almost the exact same ukulele - dark brown wood, same headstock shape and the bottom edge of the fretboard has the same triangular ridge (not sure if there's a name for that?). What stands out the most is that it has the same pink nut and saddle! It has a different logo through - instead of the B mine has, this has what seems to be the more common logo of a man holding something (a lyre according to this post -
http://www.tikiking.com/uke_db/Biltmoredb.html). It also has four dots on the fretboard instead of 3 like mine (but still 12 frets). The post says it's made by the Williams Co. of Los Angeles in the 1950's.
-- There's also someone else on this forum who has a photo of a ukulele with the same pink nut and saddle!! (
https://forum.ukuleleunderground.com/showthread.php?12955-Williams-Ukulele-What-can-you-tell-me)
In the post purplemonkeylounge says that they bought it from an antique dealer and it's a Williams Soprano Ukulele from Williams Ukulele and Guitars of Los Angeles, circa 1950's. It's possible then that Williams Co. was the manufacturer for my ukulele and then sold it to Targ and Dinner to be distributed under their Biltmore label? The logo on the headstock of purplemonkeylounge's ukulele is Williams, but that and the interior stamp seem to be the only discernible differences.
The dates listed are a little confusing though -- hendulele and river_driver both say it matches the shape of Lyon and Healy's bridges from the 1920's which doesn't match the 1950's date from the Williams Co. posts, so I want to compare and understand that. Maybe the Camp Ukes river_driver mentions are connected somehow - maybe related to the distributor or a parts manufacturer??
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So about the logo -- pretty much all the Biltmore listings I'm seeing have the man with the lyre as the logo:
-- a Biltmore baritone
https://www.stubblebinelutherie.com/restoration-queue/biltmore-baritone-ukulele)
-- ukulelecowboy's Biltmore baritone (
https://forum.ukuleleunderground.co...w-Photos-of-the-Collection&highlight=biltmore -- the photos aren't showing up for me anymore though! But when I creeped a few days ago it had the man-with-lyre logo)
-- a Biltmore concert
https://www.worthpoint.com/worthopedia/antique-vintage-biltmore-ukulele-104955252 - seems like a similar size, same number of frets, but has a different fret board since it has 4 little dots instead of 3.
I have found ONE other listing for a Biltmore ukulele with a similar logo! It has the same pink nut and saddle, and the same number of little dots on the fretboard too! (
https://picclick.com/Vintage-Sopran...ChicagoExtended-Fingerboard-391908825179.html) Only problem is that only the thumbnail photo has been preserved in the listing but the original images seem to have been deleted. I'll see if there's a cached snap of it or the original eBay listing somewhere, but that seems unlikely.
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Next steps:
-- what is the connection between Biltmore, Targ and Dinner, and Williams Co.?
-- why are there different Biltmore headstock logos: (1) a script B and (2) a man with a lyre?
-- river_driver, hendulele and EDW say its bridge matches the shape of Lyon and Healy's bridges from the 1920's, so I want to see if there's a connection to Biltmore, Targ and Dinner, or Williams Co. that can help pin down the date (for now it seems most likely it's from the 1950's?)
-- EDW commented about Harmony making most Biltmore brand instruments, so I want to look into that
-- what's up with the fretboard having 3 dots versus 4 dots?
-- seems a longshot, but it'd be cool to find a catalogue listing my ukulele!
-- anything that could show if it could be purchased in Hawaii and when (to try and pin down if it was a gift from my grandpa or great-grandpa)