The Marshall Tucker Band is as old as the CMA Music Festival. Both were born in 1972, and both have have experienced changes in recent years. Fans at this year's Kick-Off Concert at the Chevrolet Riverfront Stage will find out that both have the same infectious energy today that they did 40 years ago. Maybe even more.

MTB singer Doug Gray remembers playing Fan Fair "back in Roman times." He paced around his house, practically tripping over his own enthusiasm as he talked to Taste of Country about the June 4 performance in Nashville. His band is one of eight that will take the stage starting at 10AM the morning before the official CMA Music Festival begins.

“Once they put that set list down … it’s kind of like a balancing act for me," Gray says. "They put the same set list down for 11 years. We haven’t followed it yet.”

The 66-year-old and his bandmates play 140 shows a year, spending over 170 days on the road together. They're a tight-knit group, spending lunch and time between gigs together, rarely growing tired of the stories and the memories. Gray has stories, but he spends more time looking toward the future than the past during his conversation with ToC.

Once they put that set list down … it’s kind of like a balancing act for me," Gray says. "They put the same set list down for 11 years. We haven’t followed it yet.

“Without a doubt, 25 years from now somebody will be talking to Zac Brown and he’ll be picking and choosing these shows like we do and going out there and having a great time," Gray says explaining how the Zac Brown Band is leading the next generation of southern rockers. "He’ll be sitting on the phone talking about who’s the next one in line.”

The line between southern rock and country has always been slippery, and lately fans have stopped caring about who's on which side. Gray admits that yesterday's southern rock bands would be today's top country acts.

“I was sitting yesterday listening to some of our original records and some songs off our very first record, and there are songs on there that’s more country … we were leaning more towards George Jones than we were towards Kid Rock.”

Great music is great music, and it's almost always driven by nearly unmatched passion for giving fans a moment to fall into. That's his secret to success long after the Marshall Tucker Band's charting career has faded away like the last town's water tower in the rear view mirror. These men aren't just living on a legend.

“The memories of the music will always linger on, and I think that’s because we cared so much and was so passionate … our destiny was to be involved in something that was monumental.”

The Zac Brown Band are one of a number of acts covering hits like 'Can't You See' and 'Heard It in a Love Song.' The first was covered recently on both 'American Idol' and 'The Voice,' two shows Gray watches regularly. He loves seeing his music touch younger fans like it did the men and women of the 1970s and '80s. He loves the passion, although he admits the crowds are different.

“I do see people joining together more. I probably haven’t seen one fight, or one person pass out on the floor in the last 10 years.”

The memories of the music will always linger on, and I think that’s because we cared so much and was so passionate … our destiny was to be involved in something that was monumental.

“Kenny Chesney, he came up to me one time and says ‘Man how do you get that crowd off like you do?’" Gray remembers. "This is before he opened. We played a place called the Pit down in Florida. He didn’t have a record out yet.”

The two chatted and whatever Gray said the Tennessean took to heart. It's tough to find a more passionate singer than Chesney today. Both he and the MTB were built for careers that last decades, not years. That's rare.

“After 10 years most bands are ready to say ‘I think we oughta give it up, buddy,'" Gray says laughing.

Alos playing the free CMA Music Festival Kick-Off Concert are Shooter Jennings and the Waymores Outlaws, Lindsay Ell, Small Town Pistols, Terri Clark, Dallas Smith, the Grascals and Brazibilly. The 2014 CMA Music Festival officially begins on June 5 with 450 artists performing more than 200 hours of concerts on 11 different stages.

Look for highlights of the festival to air on ABC later this summer.

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