Uber Pro Audio has reported that a D-18V was part of LaMontagne's gear in that time before he mainly switched to Bourgeois guitars.

In This Photo We See Chad Channing Using An Martin D-18 Guitar.

In this video from LA based guitar shop "Norman's Rare Guitars" Goldsmith plays his '66 Martin D-18 which he bought there. He also states that this was his main acoustic on the album "We're all gonna die" (2016).

In this article on Martins official website they talk about Hank’s Martin D-18. Although his main guitar was a D-28 he did own a D-18. “Hank was very fond of Martin guitars and owned several of them. This D-18 was purchased by Hank in 1947 from Art’s Music Shop in Montgomery, Alabama. The guitar was featured in at least one of Hank’s promotional photos. Hank ended up giving the guitar to his bandmate Curley Williams, who used it for several decades. The guitar eventually sold at Christie’s “Country Music Sale” auction, where Martin Guitar acquired it.“- from the article

At :14s of this video you make out that Townes is playing a D-18.

In this session video from 2012 Bahamas can be seen playing a Martin D-18.

Gifted to Sweeney by Neil Diamond. It is featured in this January 9, 2018 MONO Blog interview, mentioned in this January 22, 2018 Acoustic Guitar interview and listed among Sweeney's gear in this April 1, 2021 Premier Guitar interview.

MONO Blog, January 9, 2018, "What’s In The Bag: Matt Sweeney"

These days, Sweeney carries a Martin D-28 [sic] acoustic in his Vertigo Acoustic Guitar case, a gift from the friendship with Neil Diamond. We couldn’t quite believe it ourselves talking to Matt Sweeney, so best if you heard it from the man himself!

[https://blog.monocreators.com/uploads/2018/01/IMG_0376-2.jpg]

Why did Neil give you the guitar?

Because Neil Diamond is the coolest.

But the back story is thanks to Rick Rubin I’d played guitar on Neil’s Home Before Dark album, along with the true guitar gods Smokey Hormel and Mike Campbell. It was a great experience – the album was all acoustic and all live takes.

A couple years after that, Smokey and I both happened to be hanging out in LA near Neil’s studio one afternoon, and dropped by to say hi to his studio manager Sam. Neil hears we’re in town and asks us to come back later that night to do a demo of a new song with him. We were beyond stoked. It ended up being a super fun unplanned late night hang/recording session. I think the song was called “Alone At The Ball”- it was a cool loner-style number.

At some point Neil said, “Hey you gotta check out this guitar, it’s in that case.” I opened the case and there’s this incredible looking Martin, all smoked-out and badass with the pickguard missing. It was like a dream. I played it a little and he said, “Yeah man, I had a feeling you’d sound good on it- take it back to New York, it’s yours.”

I laughed and blurted out “No f-ing way!”

He goes “Matt – it’s gonna get sold if you don’t take it, so get it outta here!”

I really couldn’t say no. Neil is a gem, straight up.

What do you know about the history of the guitar before Neil Diamond gave it to you?

I never asked cuz it’s my lucky object. I was told it’s from 1969 or by a guitar dealer who looked at the serial number.

What feelings do you have about the guitar, and what sets it apart from other acoustic guitars you’ve played?

Well, cuz of how I got it, that Martin makes me feel lucky and loved. It’s also insanely easy to play and has this particular dark and mellow sound – one of those rare “damn, this thing feels and sounds perfect” guitars. It’s also really fun to play single note stuff on for some reason. I always feel kinda relaxed and confident when I play it. The strings have been changed like twice in all the time I’ve had it.

What recordings have you used this guitar on, and what is your favourite recording moment with the acoustic?

Pretty sure I used it on Adele’s version of The Cure’s Love Song – that was a live first or second take deal. I think I was like “it’d be cool to bust a guitar solo on this beat up acoustic” and it worked.

What happened to the pickguard on the guitar?

I would love to know, and I’m also glad I don’t know.

What is your favourite song you’ve written on this guitar, and what is it about?

Maybe a song no one has heard yet called Good To My Girls – I wrote the chords and melody in Malibu lurking on a park bench with the Martin and watching Hedi Slimane do a photoshoot. Much later these NSFW words that my friend Bonnie Prince Billy sent me ended up matching the melody perfectly and the song was finally finished. It’s about a guy justifying his actions.

We haven’t recorded it yet, but I love playing it.

My Martin recently gave me another song I wrote with Bonnie Prince Billy for Songhoy Blues, an incredible band from Mali. It’s called Time To Go Home. It has a guitar part with chords and melody played simultaneously – the Martin makes it easy to do. That song will be coming out on an EP on Fat Possum records this winter I think.

(...) Have you got more rad stories about the guitar?

Brought it over to Cowboy Jack Clement’s home studio and John Prine was there and we ended up demoing a version of Love Minus Zero No Limit just for fun. That was rad.

Acoustic Guitar, January 22, 2018, "Through his web series ‘Guitar Moves,’ Matt Sweeney talks with some of the biggest names in guitar"

In an episode of Guitar Moves with singer-songwriter Cass McCombs, Sweeney exchanges some fingerpicking tips and plays them on his only acoustic guitar, an instrument of special provenance. Sweeney played as a sideman on Neil Diamond’s 2008 album Home Before Dark, and after the record was released made an impromptu visit to the singer-songwriter’s Los Angeles studio. “There were a ton of guitars lying around, as Neil was thinning his collection. He just handed me a really nice late-’60s Martin [D-18] and said, ‘I think you might like this. You know what, you should have it.’ It was great, because I had predicted the only way I’d ever get a Martin was through somebody’s extreme kindness.”

Premier Guitar, April 1, 2021, "Matt Sweeney Loves 'Guitar Playing That You Don’t Understand'"

Guitars

• 1969 Martin D-18 (a gift from Neil Diamond)
• 1976 Gibson ES-335TD
• James Carbonetti Savagist Bo Diddley-style guitar

Amps

• Austen Hooks converted Bell & Howell projector amplifier
• Will Oldham's Music Man HD-130

Effects

• Nuñez Amplification Dual Range Boost
• Echopark F-1 Germanium Fuzz

Strings

• La Bella Jazz Flats (.012–.052)
• D'Addario flatwounds (.012–.052)

In Premier Guitar's Pixies Rig Rundown of February 12, 2014 it tells us:

Thompson keeps it single-coil simple with two stock vintage Teles and two ’50s Martins—a D-28 and a D-18. When he needs an angrier tone, he relies on the P-90 in his cherry 1963 Gibson SG Jr.

In this video for the ‘Old Grey Whistle Test’, Kris Kristofferson can be seen using a heavily played Martin D-18 for “Loving Her Was Easier (Than Anything I’ll Ever Do Again)”

According to Premier Guitar interview, Welch uses 1939 Martin D-18.

Janek ma w swojej kolekcji tego Martina od września 2021 roku.

Tim Christensen playing a 1959 Martin D-18 Guitar at the legendary Normans Rare Guitars