Nevertheless, someone at HBO Pictures sensed "The Late Shift's" potential to be a TV industry version of "Barbarians at the Gate," the scathingly funny HBO docudrama about corporate raiders in the '80s. And maybe it could have been, with the right screenwriters -- namely, Garry Shandling and his staff from HBO's piercing, ruthless late-night talk show satire "The Larry Sanders Show."

But Carter's adaptation (with George Armitage) is flat and lifeless; not even an ace spoof director like Betty Thomas ("The Brady Bunch Movie") can wring an ounce of comic juice from it. And even after years of myopic attention to his subject, Carter still can't explain What It All Means. In lieu of a point, the movie (which debuts on HBO at 8 p.m., February 24 and repeats at 8 p.m., February 27 and 10:30 p.m., March 3) offers an opening banner that reads, "Believe it or not, the following is based on the truth," and a closing one asserting, "There's no business like show business!"

Rather than another "Barbarians," "The Late Shift" turns out to be one of HBO's biopics, like "Stalin" and "Truman," where the makeup is the star. Pity poor Daniel Roebuck encased in a latex chin as Leno (actually, he looks more like Eric Stoltz as the deformed kid in "Mask") and John Michael Higgins with a gapped denture stuck over his uppers as Letterman. (Letterman has been quoted as saying, not fondly, that Higgins' body language makes him look like a hyperactive chimp; actually, it's more like a stogie-powered human windmill.) Rounding out this living waxworks is impressionist Rich Little as Johnny Carson. Hiyo!

As if the makeup weren't humiliation enough, Roebuck and Higgins have to enact Carter's dramatic scenes of Dave and Jay, two of the least emotionally open personalities in the biz, being, you know, sad and reflective. If you thought "Nixon" was unappealing...

Don't get the impression that "The Late Shift" is an unintentional hoot, though. It doesn't even rise to the level of kitsch. It's just plain dull. Will anybody but fellow TV Geeks care that Kathy Bates is playing Leno's foul-mouthed manager Helen Kushnick as an even scarier obsessive than her Annie in "Misery"? Or that Ed Begley Jr. is a ringer for CBS exec Rod Perth? Or that Treat Williams has dared to assay powerful Zen superagent-turned-mogul Mike Ovitz? (Actually, Miles Drentell on "thirtysomething" was a better Ovitz spoof than Williams' -- is my geekdom showing?)

Far more entertaining, and telling, than any TV Geek tout sheet is the continuing tragicomedy played out nightly by Dave and Jay themselves. Buoyed by NBC's ratings resurgence, Leno's "Tonight Show" is on top now, a victory that must be sweet vindication to the underdog star. Leno has put his own stamp on the show, changing the set to resemble his favorite milieu, a comedy club. He has also borrowed liberally from Letterman -- doing more taped remotes -- and Carson -- ripping-off Carnac in an inane bit called "Beyondo," where Leno's disembodied head floats around barking out predictions of the future.

Oddly, though, while Leno has gotten more cocky and competitive, it hasn't made him more interesting or likable. He's still an overbearing lapdog licking your face and offering to fetch, fetch, fetch, all night long if you want him to. Is there such a thing as a Jay Leno Fan? And can such a person be rehabilitated?

Meanwhile at CBS, Dave's all dressed up in Armani for his 11:30 slot and -- whammo! -- his new network has taken such a dive in popularity, it can't even deliver him a decent-sized audience. Not to mention, that palooka Leno is sitting where Dave wants to be and Dave can't even take a night off because Leno never takes a damn night off and, oh, was it all worth it?

Sure, Dave looks happy, perky even, but maybe that's the Prozac talking. Some nights, he gets stuck on a phrase and keeps repeating it over and over, like that "Oprah, Uma" bit on the Oscars last year, even though nobody's laughing. Lately, it's "You da man!," bellowed without warning to bandleader Paul Shaffer.

But every now and then, when everything's clicking, Dave's brilliance hits you full force (as last Monday's prime-time video highlights special attested). There hasn't been a late-night host so relaxed, so alive, in front of the camera since Carson. Letterman's Steve Allen-inspired man-on-the-street bits get weirder and funnier all the time (his music video tribute to Moe, the meat slicer at New York's Stage Deli, was an instant classic). His nasty ol' bastard edge is honed to a fine comic gleam these days, especially when he's sadistically instructing, via hidden microphone, shopkeeper Rupert Jee on how to creatively annoy strangers in public.

If Letterman's comedy seems harsh, remember that Carson could be pretty nasty too. In style and temperament, Carson and Letterman are spiritual father and son (and Carson made it plain that, had NBC had the courtesy to give him a hand in naming his successor, he'd have chosen Letterman). And therein lies the talismanic significance that Johnny's "Tonight Show" holds for Dave. "The Late Shift" book and movie refer again and again to Dave's boyhood dream of hosting "The Tonight Show." Perhaps shy Dave saw succeeding Carson as a chance to slip out of his own skin, to become his hero as a way of finding -- and liking -- himself.

Which is why it's so sad that, in "The Late Shift," Letterman believes he's a failure, even after being handed the keys to the CBS coffers. For Dave, it seems that only being host of NBC's "Tonight Show" will do. It's his Ponderosa, his testing ground as a man, the place where he'll finally be able to prove -- to himself -- that he's Carson's true heir.

The rest of us don't need as much convincing.

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Does anyone care about the Jay vs. Dave show? Which do you like better and why? Join the conversation in "Television" in  Table Talk.