As a former member of rock 'n' roll legend Buddy Holly's band, the Crickets, Niki Sullivan is more critical than most people when it comes to evaluating the many musicians who have imitated Holly over the years. 

But the Texas-bred guitarist has nothing but praise for John Mueller, who portrays Holly in the San Diego Repertory Theatre's production of "Buddy . .  . The Buddy Holly Story." 

"John is awesome. Not only does he have similar physical features to Buddy, he also has certain traits Buddy had, such as his country smile, warmth and pleasant personality," said Sullivan, 59, who will join Mueller onstage for the musical finale in Friday and Saturday's performances of "Buddy" at the Rep. 

"And when he's a little nervous and his hands are at his sides, he'll click his fingernails. I caught him doing it, and asked him, `Where did you learn that?' And John said, `I didn't even know I did it.' And I told him that Buddy did the same thing. 

"He also has the shyness and the determination in his eyes that Buddy did.  And when John is onstage, he is a totally dynamic performer, just like Buddy Holly." 

Sullivan was Holly's third cousin by marriage. In mid-1955, a year before he teamed up with Holly, he came to San Diego to attend Navy boot camp. 

"I loved it, but I only lasted six months in the Navy, because I was a sleepwalker, and the Navy doesn't like sleepwalkers," Sullivan said with a laugh. "They don't want you walking off the side of a ship when you're on guard duty." 

In late 1955 Sullivan returned to Lubbock, the Texas town where he and Holly grew up. In late 1956 he was invited to an informal jam session at Holly's house. He subsequently was invited to join Holly's then-nameless band as rhythm guitarist and harmony singer. 

He and Holly quickly discovered they had the same musical heroes -- Hank Williams, Hank Ballard, Little Richard and Fats Domino, along with Muddy Waters and a slew of other blues greats. Nevertheless, Sullivan was daunted by the prospect of even jamming with Holly, who already was regarded by some as Lubbock's answer to Elvis Presley. 

"I was intimidated and afraid I was musically inferior," Sullivan recalled.  "The rest of us had musical aspirations, but nothing like Buddy. He had paid his dues, he had experience. But as the night wore on, I got my guitar out and played along. It was easy, because the music was simple. We had fun, and Buddy liked what he heard. 

"He had just been kicked off of Decca (Records); he had two releases that both failed. And he had an appointment with (New Mexico-based producer) Norman Petty, who I think was a genius . . . . We weren't trying to change the world; we were merely trying to be part of it." 

That meeting with Petty led to a new contract, and the recording of "That'll Be The Day," which featured Sullivan and made Holly a national star. The teen-age Holly and his band set off on the first in a series of grueling cross-country tours. After 14 months of almost nonstop concerts, Sullivan quit. Holly died in a plane crash barely one year later. 

"I was tired; exhausted is a better word," said Sullivan, who still receives royalties for "I'm Gonna Love You Too," which he co-wrote with Holly. 

"I didn't like the 21-hour work days, not knowing where you would be, the lack of sleep, the lack of eating on a decent schedule, the lack of everything. Buddy grew tired of it real quick, just like the rest of us.  It's demanding and demeaning. And I often said, after I left the Crickets, that nobody should ever have to live that way. 

"But Buddy handled it much better. And he was one of the few naturally gifted people who could make you feel like a friend, whether you were a fan or a co-worker or just an acquaintence. With Buddy, you always had a friend. He was real. If you never had a friend, at least you had a Buddy, and he was true to it." 

In addition to performing with Holly for 14 months, Sullivan also can take credit for suggesting the name for Holly's band. Yet while a rhythm guitarist playing Sullivan's part performs in "Buddy," the character has no spoken lines. 

The reason for this is somewhat complicated, said Sullivan, who now works as an accounts representative for Sony in Kansas City, Mo. 

Alan Janes, who wrote "Buddy" for the stage, based his book on the 1978 movie "The Buddy Holly Story," according to Sullivan. The film, Sullivan explained, was based on the first edition of "The Buddy Holly Story" by John Goldrosen. 

Goldrosen wanted to interview Sullivan for the book, Sullivan said, but the former Cricket declined because his wife, Fran, had recently given birth to their twin sons. To further complicate matters, Janes was unaware that -- after the film version he based his play on was released -- Goldrosen wrote an updated edition of "Buddy" that did include quotes from Sullivan. 

Even so, Sullivan maintains he is not annoyed that the makers of "The Buddy Holly Story" unwittingly excluded him from the film, or that the character based on him is only heard playing guitar in the theatrical version. 

"I'm not annoyed in the least," Sullivan said. "There's no way to be annoyed. Because I was there, I have the memories, and they don't."