POP MUSIC REVIEWS : From Genuine Emotion to Show Biz : Benefit: Crosby, Stills, Nash & Young honor their drummer Dallas Taylor, who needs a liver transplant, and raise funds to battle drug abuse.

Benefit concerts have turned into rock’s hottest guessing game. As soon as the official lineups are announced for these multi-act shows, fans begin speculating on who’ll show up for the de rigueur all-star jams at the end.

The guessing at events that charge more than $100 a ticket usually begins with one of the Big Bs--Bob or Bruce--and proceeds through the alphabet: R these days for Bonnie Raitt, S invariably for Sting, and so forth.

On Saturday night at the Santa Monica Civic Auditorium, the guessing lasted until just after midnight, when it was apparent that the only “extra” was the man in whose honor the concert was held: drummer Dallas Taylor.

Taylor, the original drummer with Crosby, Stills, Nash & Young, sat in with his old mates for the first time in nearly 20 years on two of CSNY’s best-known numbers, “Wooden Ships” and “Teach Your Children.”

Taylor, whose career was ruined in the ‘70s by drug abuse, has been an abuse counselor himself for about five years and learned last November that he is in desperate need of a liver transplant. He is now on a waiting list.

Saturday’s concert--which also featured Don Henley and the Desert Rose Band--was designed to focus attention on the organ donor program and to raise funds for the Freda Foundation, a nonprofit drug abuse research and education organization. It was expected to raise about $125,000.

Even though the artists said good night as they left the stage, much of the audience remained, waiting for some sort of surprise. Since David Crosby and Chris Hillman--now leader of the Desert Rose Band--were both on hand, maybe there would be a repeat of the Byrds mini-reunion that occurred in February at the Roy Orbison/homeless benefit at the Universal Amphitheatre.

Or because Neil Young and Stephen Stills had both performed, there was a chance of a partial Buffalo Springfield regrouping. Henley’s presence could have meant a partial Eagles assembly.

But the closest any of this came to reality was early in the evening when former Eagle Timothy B. Schmit joined Henley as he sang the Eagles’ 1974 hit “The Best of My Love.”

While the speculation is inevitable in a city that is home to so many celebrated musicians, the preoccupation with “surprise” and “history” tends to undercut the natural drama of the evening.

Aside from the emotional surge of seeing Taylor on stage again, the musical highlights of the night were tied strictly to individual artistry, not nostalgic repackaging. The most compelling art was provided by Henley and Young.

Their approaches were vastly different. Henley was joined by a dozen musicians and surprised the crowd with his own version of Johnny Mercer and Harold Arlen’s “Come Rain or Come Shine,” while Young paced the stage anxiously with just his own guitar.

They were linked by the independence and excellence of their material, as both men sang about troubling social concerns--Henley’s “The End of the Innocence,” Young’s “Rockin’ in the Free World”--without sacrificing idealism and hope.

Surprise guests at the end might have given the evening more of an emotional buzz, but it is unlikely that they would have matched the power and passion of Henley and Young. Yet the curiosity lingers. The mainly acoustic program was to have been repeated Sunday night, this time to benefit the California Environmental Protection Act. And Saturday you could hear people on the way out already speculating on who might join the lineup. The guessing was soon halfway through the alphabet.