You think you're watching late-night TV: David Letterman in an apron, whacking apart pork ribs with a mammoth meat cleaver.

Look again. It's Ben R. Morris, who looks a whole lot like Letterman when he grins, and even has similar mannerisms. Do people comment on the resemblance? "Only about five times a day," says the 55-year-old chef-owner of Ben's Whole Hog Barbecue.

Take Old Centreville Road almost to the Fairfax County line and you come to the red-roofed log cabin where Morris roasts hogs slowly in wood-fired brick wall ovens that line a wall.

He designed the ovens himself, with the aim of getting the outdoor, country-fair taste of roasted pork inside, year-round.

"We cook with wood. It's more work, but it's worth it," he says.

Morris knows wood, even if he doesn't think diners can tell the difference. "Hickory is the optimum, the ultimate hardwood. Hickory is like drinking a good French wine . . . just a good psychological thing. It uplifts you."

Sometimes he uses apple wood, and sometimes wild cherry.

Where does the wood come from? "We have an endless supply. A lot of good customers are in the tree business out of Winchester."

The pork that comes out of those ovens is tender. Ribs are succulent, just the right degree of crispiness. And turkey smokes well in the oven, too.

The Styrofoam plate couldn't contain our dinners; the pork ribs spilled over. The combo, ribs and pulled pork, like all platters ($7.45), comes with homemade sides and bread. Baked beans are made with northern white beans, bits of bacon, and a diced onion or two. The coleslaw won over one of our diners who doesn't even like coleslaw. Moist corn bread is made daily, as well as bread pudding ($1.25 a serving). This is bargain eating at its best.

Ben's recipes are his own. "I guess you could say our signature is the sweet potato casserole." With smoked turkey, sweet potato souffle and corn bread, Ben's is like Thanksgiving every day.

The barbecue sauce is his own blend, sweet with apple cider.

"I don't think you can affix a geography to the kind of barbecue I do," Morris says. Born in Atlanta, he says he has pursued barbecue in New Mexico, the Carolinas and Chicago.

Ben's barbecue has a celebrity endorsement, sort of. Actor Robert Duvall has eaten there. On counters are photos of the actor and the hogmeister. "He's a real nice guy, down to earth," Ben says of Duvall. "The picture was taken with one of those disposable cameras the last time . . . He asked to see the place. I gave him a tour of the ovens."

Morris seems to be a neighborhood fixture: While we ate, four Slurpee-wielding youngsters stopped in to say hello. They didn't say much of anything, but seemed to enjoy being there.

Ben's is a funky place: Flea market pig knickknacks and a poster--"Everything I Need To Know, I Learned From a Pig." The jukebox repertoire is eclectic--Johnny Paycheck, Green Day, songs in Spanish. A song for any mood.

As reader John A. Beere noted when recommending Ben's, the atmosphere is what you make of it. Ben's is near a mobile home community, wedged in between a 7-Eleven and a small strip shopping center whose social center appears to be the self-service laundry. You could pop in a load of laundry, then eat a pulled pork sandwich while it washes. (There's a $2.99 sandwich-and-beer special. Top that!)

Carryout costs $7.95 a pound for barbecued pulled pork or smoked turkey or beef brisket, $5.40 for a quart of barbecue sauce.

Pen uses the whole pig. Pigs' feet are available Sundays, chitlins daily. He says just call to order them. Also available are hog's head cheese ($2.75 a pound) and pork skins ($2.55 a bag).

Another idiosyncrasy at Ben's: The men's restroom contains a table, a microwave oven, and a large-print New York Times Cookbook, a source informs us. We didn't even want to ask.

BEN'S WHOLE HOG BARBECUE

* Address: 7422 Old Centreville Rd., Manassas, 703-331-5980.

* Hours: Tuesday to Friday, 10:30 a.m.-9 p.m.; Saturday, 10:30 a.m.-10 p.m.; Sunday, 12:30-9 p.m. Closed Mondays.

* Credit cards: Yes, plus personal checks.

* Prices: $3.75-$4.25 for sandwiches; $5.95 and $7.45 for platters, except $16.50 for a slab of ribs platter. Full carryout menu. Our bill for five complete meals came to $40.86.

* Children's menu: None, but Ben says he "works something out" and charges less.

* Low-fat selections: Smoked turkey.

* Health-conscious: Somewhat.

* Atmosphere: Very casual.

* Downside: Easy to drive by and miss.

Got a Prince William restaurant you'd like to spread the word about? Send e-mail to shumansk@washpost.com or kovachs@erols.com, or mail to: 9254 Center St., Manassas, Va. 20110