Not just another tired rockabilly relic, Sleepy LaBeef is one hulking bear of a singer/guitarist who ranges menacingly across the wide open spaces of American roots music, attacking country, blues, gospel, and rock 'n' roll with equal aplomb. He's been at it for 30 years--through a long stream of honky-tonks and obscure record labels--and now it seems to come as naturally to him as walking. Blessed with an expressive, bedrock-deep basso growl, he can sound by turns jubilant, sorrowful, or scary, all while retaining the all-important warmth that on the best of nights can turn a bar into a party. How so vibrant (and, incidentally, literate) a performer as LaBeef has remained obscure for so long only God knows, but at a time when roots rock has been wrinkled up pretty badly by herds of wet-behind-the-ears revivalists and exhausted has-beens, it's good to know that here's a genuine Arkansas-bred old-timer who can still get it up and get it moving. Tuesday, FitzGerald's, 6615 Roosevelt, Berwyn; 788-2118. Wednesday, Cubby Bear, 1059 W. Addison; 327-1662.