They're the L.A. studio musicians who played on Glen Campbell's early hits, including "Gentle on My Mind" and "By the Time I Get to Phoenix," and countless other songs that became part of America's soundtrack during the '60s and '70s. One of their biggest admirers, Denny Tedesco, remains on a mission to tell their story in the film documentary, The Wrecking Crew.

Sixteen years into the project, though, Tedesco is still trying to get it officially released. In the meantime, he's still taking the film on the road for screenings to raise money to pay for an absolutely essential element -- the rights to include some 133 recordings that help tell the musicians' story.

Tedesco is in Nashville for a Thursday night (July 21) screening to coincide with the summer convention of the National Association of Music Merchants, a trade organization of musical instrument manufacturers and retailers. The film has been screened at more than 50 film festivals throughout the world and has won awards at several of them, including the Nashville Film Festival.

The Wrecking Crew's list of recording credits is filled with iconic recordings, including the Beach Boys' "Good Vibrations," John Denver's "Thank God I'm a Country Boy," Frank Sinatra's "Strangers in the Night," Nancy Sinatra's "These Boots Were Made for Walking," the Mamas & the Papas' "California Dreamin'," the Byrds' "Mr. Tambourine Man," Sam Cooke's "Twistin' the Night Away" and Sonny & Cher's "The Beat Goes On." The list goes on, too, including hits by Elvis Presley, the 5th Dimension, Dean Martin, the Carpenters, the Partridge Family, Seals & Crofts, the Monkees, Johnny Rivers, Nat King Cole and Phil Spector's "wall of sound" recordings by the Ronettes, the Crystals and the Righteous Brothers.

And then there were soundtracks and TV theme songs, including Bonanza, Green Acres and Batman. Tommy Tedesco, Denny's late father, played guitar on those three tracks and lots more during the Wrecking Crew's heyday.

Tommy Tedesco, drummer Hal Blaine, bassist Carol Kaye and saxophonist Plas Johnson were key members of the Wrecking Crew, although the musicians themselves are hard-pressed to say how many people were in the elite corps through the years. Campbell was one of them before he found stardom as a singer and TV personality, and famed guitarist James Burton, who played on Merle Haggard's classics from the '60s, was a member, too.

"I would say there is a good 20 or 30 musicians who were the demo guys in L.A. at that time," Denny Tedesco told CMT.com. "When the demos started becoming hits, they were the guys to call."

As for the group's name, he said, "These guys don't remember it being called the Wrecking Crew, but Hal said someone once said, 'These guys are going to wreck the business.'"

Instead of wrecking the business, they expanded it.

The film itself is a fascinating account of how the session musicians turned great (and sometimes less than great) songs into recording masterpieces. It's filled with inside information and tidbits, such as the fact that they routinely recorded four songs in a three-hour session and often turned around entire albums in a single day. Among the insights are how Kaye's bass line transformed Sonny Bono's arrangement of Sonny & Cher's "The Beat Goes On" and how she came up with the distinctive riff that kicks off Campbell's "Wichita Lineman."

Tedesco began work on the film in 1995 with a single interview featuring his father, Blaine, Kaye and Johnson.

"My dad had cancer and was dying," he said. "I wanted to get his history down and the history of his peers and friends. I just put them in a roundtable and started talking."

The project evolved from there, and Tedesco continued to interview the musicians, producers and artists following his father's death in 1997. In fact, he's still interviewing musicians for segments to be included in an upcoming DVD release.

"It was all self-funded," he said. "I thought I was going to knock this out in two years and get somebody to pick it up. But no one would jump on it."

Even friends who supported the idea told him the film could never be released because of the costs of licensing the music. So far, their prediction hasn't come true, but the problem has caused substantial roadblocks along the way.

"I passed a certain line where you go too far, where you can't turn back," said Tedesco, whose work as a freelance video producer includes projects for TV Land and infomercials for Time Life. "Around 2006, I realized I'm not going to get this made unless I cut the film. I had no choice. If it wasn't such a personal story, I could have maybe walked away from it. But it got way too personal because it was my father, and it was his last words, in a sense."

He's already sunk more than $500,000 into shooting and editing the film and is about $200,000 away from the $300,000 needed to pay for the rights to feature the music in the film. He has no ill will against the companies who control the use of the songs and recordings, saying they deserve to be paid. It's just that licensing 133 songs is a costly proposition.

"It sounds like the publishers and the labels are the bad guys, but it's not the case on this one," he said. "Could they give it away to this doc? Absolutely. It's a documentary. It's never going to make money. Even a Michael Moore or Ken Burns, those documentaries are one in a million."

In the meantime, Tedesco has partnered with the International Documentary Foundation, a nonprofit, tax-exempt corporation, to secure private donations and sponsorships to help pave the way for a theatrical release of the film, TV airings and the DVD release.

"At this point, I don't want to blow it and just dump it out there," he said. "The BBC wants it, PBS wants it, but no one can come up with a big enough price to pay everything off. There are a couple of possibilities of people underwriting the whole project. It doesn't make sense to me. I'm very proud of the film. The film stands by itself.

"Me, as a salesperson," he laughed, "maybe I'm not so good. What can I say? Someone said, 'You're really a great filmmaker.' I said, 'Well, when you take 15 years, you better be.'"

For more information about The Wrecking Crew, visit the film's website.