Like the Beach Boys, the Oaks have a few too many crow's-feet to be called ''boys'' anymore. But that should be the least of their worries. Always one of the tamest vocal groups in country they came out of tame white gospel, after all they've now sunk to new levels of homogenization. When the songs on their new album, Unstoppable, aren't total bland-outs, they're dorky novelty tunes, such as ''Baby on Board'' (the romantic kind, not somebody's infant) and ''Love This Cat,'' a failed attempt at rockabilly replete with a kitten's meow at the end. Like that polyester leisure suit in the back of your closet, the Oaks seem impossibly quaint and old-fashioned these days. Of course, they see themselves differently. In ''When It Comes to You'' they sing: ''I'm a little bit wild/A little bit crazy.'' In your dreams, boys, in your dreams. C

