Staggered by death and creative exhaustion, the southern-rock movement is in danger of losing its identity as a distinctive regional sound. In pursuit of commercial success, the Marshall Tucker Band and the Charlie Daniels Band have moved toward a rootless pop-country sound, while the Outlaws and .38 Special have moved toward the ubiquitous "album-oriented-rock" (AOR) sound. These bands also have shown a new willingness to use writers and producers from outside the region. The resulting records are often appealing, but lack the geographic roots that once made southern rock a proud showcase.

The Marshall Tucker Band--which appears at the Merriweather Post Pavilion Sunday--was the first southern rock band to crack the Top 40 after the Allman Brothers Band's pioneering success. In recent years, the Marshall Tucker Band has suffered bassist Tommy Caldwell's fatal auto accident and three consecutive poorly selling records. Hoping to change its luck, it has sharply changed directions with "Tuckerized" (Warner Bros.), its 12th album in 10 years. For the first time, the band has relied heavily on outside material; only two of the 10 songs are original. Moreover, producer Gary Klein (who has worked with Dolly Parton and Glen Campbell) plays up the pop-country melodies and plays down the "redneck boogie." This shift makes sense, for the band has always overemphasized its sluggish rhythm section and underemphasized its superb leader, Doug Gray.

If Gregg Allman is southern rock's best blues singer, Gray is its best country singer. Gray croons Tim Hardin's "Unforgiven" with a rich tenor and a Willie Nelson-like understatement. While Gray brings out melodies, reed player Jerry Eubanks and guitarist Toy Caldwell bring out the full, satisfying harmonies. Caldwell plays intricate jazz guitar fills on the western swing of Guy Clark's "Heartbroke" and weeping pedal steel guitar on "Unforgiven." The songs by Clark, Hardin, Tom Snow and Randy Newman are so much better than the rest of the material that the album seems unbalanced. The first single is Newman's "Mr. President (Have Pity on the Working Man)," written as a droll anti-Nixon cabaret song but transformed by the Marshall Tucker Band into a foot-stomping anti-Reagan hoedown.

The Charlie Daniels band--which appears at the Pavilion Aug. 29--also benefits from outside writing on its new album, "Windows" (Epic). Dan Daley's "Still in Saigon," which leads off the album, was a huge hit single last spring. Its carefully sketched portrait of a Vietnam vet still haunted by memories haunts the listener the same way. The song's urgency gives Daniels' sextet a reason to play with the passion that once distinguished southern rock. The other nine songs--all penned by Daniels and/or other band members--give the group no such reason. These songs rather unconvincingly summon up country & western stereotypes of rambling men, loose women, homesick singers and a kindly deity. John Boylan's slick production pulls the band's roots out of Tennessee and leaves them dangling in the anywhere pop sound of Boylan's other projects: Quarterflash and Boston.

The Outlaws, who come to the Capital Centre July 9, have pared down their sound to fit the modern AOR format. Once a boisterous triple-guitar sextet like fellow Floridian Lynyrd Skynyrd, the Outlaws are now a streamlined two-guitar quartet working with hard-rock producer Gary Lyons. The Outlaws' new album title, "Los Hombres Malo" (Arista), comes from the late Lynyrd Skynyrd singer Ronnie Van Zant's nickname for them. The music, though, is closer to the international platinum-rock sound of R.E.O. Speedwagon. Hughie Thomasson (the only original Outlaw still in the band) and Freddie Salem adapt quite well. Instead of lots of cluttering guitar notes, they fashion clear, arching lines that carry the strong melodies forward. The verses often contrast a smooth lead guitar and lead vocal against a choppy rhythm arrangement. The four songs by Thomasson and Salem are the record's weakest; the potential singles come from recent bassist Rick Cua and outside writers Sammy Hagar, Jim Peterik and Joe Russo.

Led by lead singer Donnie Van Zant (Ronnie's younger brother), .38 Special leaves its southern roots even further behind than the Outlaws do. Gone, on its new album "Special Forces" (A&M), are the country drawl and rhythm & blues of southern rock. In their place are the high-pitched guitars, straight-ahead 4/4 beat and hi-tech production of modern hard rock. Producer Rodney Mills focuses the guitars of Jeff Carlisi and Don Barnes into clean, soaring lines calculated to get adolescent juices flowing. All nine songs are originals, but eight of them are forgettable formula exercises. The ninth, "Caught Up in You," is so immediately catchy that it could be this summer's big single. As the appealing melody line is repeated through different chords, the rhythm builds from a tentative tick-tock to a forceful, triumphant climax.

Two southern rock bands have preserved their regional roots in the face of commercial pressures. The Rossington-Collins Band, built around three of the four survivors of Lynyrd Skynyrd, have released two emblematic southern rock albums. The fourth Skynyrd survivor now leads the Artimus Pyle Band. Pyle's muscular drumming drives the quintet through "A.P.B." (MCA), its debut album, produced by Jerry Eubanks, Doug Gray and George McCorkle of the Marshall Tucker Band. The rhythm & blues emphasis of lead singer Darryll Smith is balanced by the rocking boogie tendencies of lead guitarists John Boerstler and Steve Lockhart. This balance is the original hybrid that inspired the Allman Brothers and Lynyrd Skynyrd to the sweaty, blunt songs that once spoke for the South's long-haired rednecks. The nine original songs on "A.P.B." don't reach the heights attained by those two bands, but the Artimus Pyle Band is definitely keeping an endangered tradition alive. They will appear at Desperado's late in July.