A STRANGE thing is happening in country music. The youngest, most adventurous performers are teaching their established elders how to be old-fashioned.

"John Anderson 2" (Warner Bros. BSK 3547) is the kind of album that George Jones or Lefty Frizzell might have made 20 years ago. Anderson has a gorgeous George Jones voice that throws out each syallable with a tough belt and then holds the syllalb in a counterbalancing seductive purr.

Anderson also has the storytelling flair of Frizzell or Merle Haggard, establishing plot and characters so well in the first three minutes of a song that you hang on that last verse to hear how it turns out.

"John Anderson 2" includes Frizzell's "I Love You a Thousand Ways." The song starts in grand old-fashioned style, with Buddy Spicher's fiddle and Pete Drake's pedal steel guitar bending notes till they weep. Anderson then comes in and proves his voice can squeeeze as many tears out of a bent note as any fiddle or steel guitar.

Anderson is really at his best on the traditional weepers. Whether trying to forget "The Same Old Girl" or lamenting thta "You've Got the Longest Leaving Act in Town," Anderson is able to baret the hurt without ever getting sloppy. He is an admirable example of how a man can cry without losing his dignity.

The big hit single from "John Anderson 2" is Billy Joe Shavers' "I'm Just an Old Chunk of Coal (But I'm Gonna Be a Diamond Someday)," a spirited fiddle song full of puns and honky-tonk authenticity. It's also the title song of Shavers' own new album (Columbia FC 37078).

Shavers belongs to that school of songwriters (Rodney Crowell, Guy Clark, Lee Clayton, Ray Wylie Hubbard and Keith Sykes) who supply the songs for Willie Nelson, Waylon Jennings, Jerry Jeff Walker and the Johnny Cash family. Shaver is the macho man of the class; his every song tries to prove "I'm a pistol-packing papa with a million dollar smile; I'm fit to kill and going out in style."

Shavers' assets are boundless enery and a knach for putting words together. Every song has a jingly melody and a bouncy beat. His liabilities outweigh his assets, however. Though his wording is clever, his themes are shallow. This songs aren't about real people; they're about Western cliches -- heroic cowboys and roaring pickups -- and sexist stereotypes -- easy senoritas and nagging wives.

Moreover, he can't sing too well. His version of "I'm Just an Old Chunk of Coal" is a dusty, dull performance. It took John Anderson to shine it into a diamond.

Much better than Shavers' record is "South Coast of Texas" (Warner Bros. BSK 3381) by Guy Clark, one of the very best country songwriters. His four-minute songs are crammed with more details about characters and places than most two-hour TV movies.

It's these details that carry Clark's second album. He writes about Coleman Bonner, a young mule breaker who refuses to leave "New Cut Road" in Kentucky where he can "drink that sourmash and race that mare." "South Coast of Texas" is peopled with Cajun shrimp-boat crews, oyster shell roads and hurricanes that teach "snakes how to swim and the trees how to lean."

Clark has even less of a voice than Shavers, but makes better use of it. He sings within his limits in the dramatic folky style of Bob Dylan or John Prine. He's helped quite a bit by his friend, Rodney Crowell, who produced the album and co-wrote two songs. Crowell uses Emmylou Harris' Hot Band to provide lovely, old-fashioned understated backing. The result recalls the days when there was barely a whit of difference between "folk music" and "country music."