If age-ists were looking for a metaphor for the Crosby, Stills, Nash & Young reunion tour, they'd have found it yesterday with the sight of 57-year-old Graham Nash being pushed up to the podium at Madison Square Garden in a wheelchair.

Factor in him, Neil Young in his choochoo hat, David Crosby and his second-hand liver, Stephen Stills' glass-gargling whiskey tenor and assorted blown braincells, and you have a legendary quartet that will play the Air Canada Centre on March 30 with all the grizzled pluck and pride of a veterans parade.

Nash, of course, is a recent casualty. He broke both legs in a boating accident "at 4:06 (p.m.) on September 12th," the Brit-born singer said with dry exactitude in a satellite press conference (which he attended against doctor's orders).

'Backbeat'

He'd been riding the front of his boat in choppy waters for "the experience of weightlessness" off Hawaii with family members when a second wave sent the boat up toward him. "There was a two-hour trip back to port. That was special. And the sound of both legs breaking. As a musician I have a sensitive ear, and I wish I could have sampled it and used it as the backbeat on some record."

Ouch. "But I'll be out of this wheelchair in four weeks, and I'll be ready to rock (when the CSN&Y2K tour begins Jan. 24 in Detroit). Nothing's going to change that, if I have to get up on crutches and sit on a stool onstage."

"We'll give you an acoustic stool and an electric stool," Crosby interjected.

"I don't know if I want to see an 'electric stool'," added a wry Neil Young, 53, whose participation was key to both the CSN&Y tour and to the release of their new album, Looking Forward.

Seeing them all together being jovial, brothers in workclothes and long (albeit thinning) hair is a strangely comforting experience for anyone old enough to remember when there was a war to protest. The guys who gave us the angelic harmonies of Suite: Judy Blue Eyes and the searing comment of Ohio, after all, only came together in the first place because they didn't get along with others.

Crosby had split from The Byrds, Young and Stills from Buffalo Springfield, Nash from The Hollies. Together, they were equally fractious, releasing only the classic album Deja Vu and the live album Four Way Street before going separate ways and reuniting in various combinations. The last serious talk of a tour was in 1989 when they released American Dream, but Young pulled out of the plans.

So their last tour remains the 1974 trek, which brought them to Varsity Stadium in a show promoted by a young guy named Michael Cohl, whose company, TNA, is handling this one. "This show will be slightly different in that I will be awake," quipped Crosby, the biggest drug and lifestyle casualty in the group. What was the difference between then and now? "I believe we are a little more mature, compassionate and sensitive of each others' feelings," said Nash. "We were kind of separate, we all had our separateness back then. Our relationship has never been better."

'Compatriots'

Added Young (who indeed used to travel separately from the others): "We've been through enough together to be interesting compatriots."

Young's thaw came last year, when he was with Stills going over old tapes for a Buffalo Springfield box set. Young, who was in the midst of recording his own upcoming album (to be called Silver & Gold) heard a track the other three had recorded for a self-produced album and decided to jam. One thing led to another and he offered the group their choice of his own new songs.

But these aren't the same old free-spirited hippies. Young bemoaned the tour somewhat, saying, "I'm gonna miss driving my girl to school in the morning, being part of the family." Stills, 54, has a three-year-old son, and Crosby, 58, a four- year-old, inspiring similar family concerns.

But, added Young, the inspiration to tour is there because, "I don't think we ever really reached our potential the first time. There's a lot of unfinished business with this band."

Tickets for the Air Canada show go on sale Saturday through Ticketmaster, Air Canada Centre box office (no first day sales). The wristband policy is in effect today at 10 a.m. Limit eight tickets per person.

CSN&Y File

Which hit songs belonged to which combination of Crosby, Stills, Nash & Young?:

CSN&Y: Woodstock, Teach Your Children, Carry On, Our House, Ohio, American Dream.

CS&N: Marrakesh Express, Suite: Judy Blue Eyes, Wasted On The Way, Southern Cross, Just A Song Before I Go.

S&Y: Long May You Run.

N: Chicago.

S: Love The One You're With.