Despite its success, the first Broadway musical to use rock and roll songs was dismissed as a trivial fluke at the time of its premiere in 1960--the same year draftee Elvis Presley starred in G.I. Blues. But over the years it has proven a durable and delightful caricature of its era. One reason is Michael Stewart's script, about a pelvis-twitching singer just inducted into the Army and the efforts of his manager to capitalize on the event by having the star give a farewell kiss to a fan in front of millions of Ed Sullivan Show viewers; the sly spoof of a pop-culture clash between innocent but incipiently rebellious teenagers and the show-biz shysters who want to exploit the new "youth market" is sometimes funnier today than it was originally. Another appealing factor is the zesty and memorable score by Charles Strouse and Lee Adams, with its witty blend of hillbilly rock, Pat Boone pop, low-key jazz, and Copland-inspired counterpoint (the teen-gossip choral number "The Telephone Hour" is a musical-comedy classic). This touring revival, breezily directed by Gene Saks and featuring rich and glossy new orchestral arrangements by the brilliant Peter Matz, stars master tap dancer Tommy Tune as the manager. But the real strengths of this ensemble piece are the energetic supporting cast--especially Lenora Nemetz as Tune's taken-for-granted girlfriend, Susan Egan as the teenager chosen to receive Birdie's so-long smooch, Jessica Stone as a crazed fanclub president, and Marc Kudisch as the beer-guzzling slob of a singing star--and the material itself, with its time-capsule references to going steady, Ed Sullivan, Trailways buses, Daisy air rifles, and a peacetime draft...OK, so some things haven't changed. Auditorium Theatre, through April 11 (50 E. Congress, 902-1500). Tuesdays and Thursdays, 7:30 PM; Wednesdays, 2 and 7:30 PM; Fridays, 8 PM; Saturdays, 2 and 8 PM; Sundays, 3 PM; Monday, April 6, 7:30 PM. $12.50-$50.