"GUITARS, CADILLACS, ETC. ETC." Dwight Yoakam. Warner Bros. The debut album from L.A.'s fast-rising honky-tonker (who headlines the Roxy on Tuesday) has a brambles-in-his-britches, chaw-in-the-jaw believability that would be best appreciated blaring out of a jukebox in a beer-soaked bar. Fusing the musical punch of early rock with the emotional honesty and twang of gen-u-wyne C&W, this Kentucky-born transplant to the West Coast also has the wrenching voice of a potential Hall of Famer--a steeped-in-heartache composite of Hank Williams and Merle Haggard with a dash of Jimmie Rodgers' exuberant yodeling. Yoakam is an equally impressive writer in songs like the tear-stained "It Won't Hurt" and his hellbent-for-the-Promised-Land duet with Maria McKee, "Bury Me." If there's anything wrong with this utterly electrifying debut it's that its mere half-hour length is far too little time with as talented a newcomer as Yoakam.