The burly athlete sat perspiring in a sweatshirt inside his three bedroom rambler in Bowie, Md., confident after a workout, hinting arrogance. After all, he had walked off, so to speak, with the Boston Marathon last year - a trophy in his class - a victory that had not gone unnoticed. The proof was assembled in his living room - a producer from NBC, a camera crew, a reporter, all lured by his PR man to launch wheelchair Olympian Dave Williamson as the Bruce Jenner of handicapped athletes.

The producer wanted a dramatic long-lense shot of the wheelchair rolling toward the Lincoln Memorial. He would shoot the sequence from atop the Washington Monument. It would be pure Hollywood. Inspirational. Like "Rocky." He could virtually guarantee three full minutes on the Today Show.

The jock nodded, dreaming of the day he might sign a six-figure contract to careen about airports, scattering suitcases on the way to the rent-a-car counter. "I'd love to have Farah Fawcett-Majors rub shaving cream all over my face," he grinned. The jock was no different from any other budding Namath or O.J. or Reggie Jackson. He could learn to live like a star.

The selling of Dave Williamson certainly has all the elements of hype for a cause.

"You just don't see people in wheelchairs selling cars on TV, or going to McDonald's, or rolling around in the background in movies," he says.

He wants to change all that, boost the image of the disabled as normal, independent people, and, little by little, help society over its psychological discomfort in dealing with 35 million handicapped Americans.

So you enter marathons, you change the image. You go on TV, you change attitudes. You change attitudes, you make life a little easier for everyone.

Williamson i paid $36,000 a year as a government watchdog for the Department of Housing and Urban Development to do just that - to make sure handicapped Americans get a few breaks. He claims to be tough. "You could say I'm more of a bastard than easy to get along with, a leader, not a follower, aggresive. The inner Dave Williamson is not affected by his disability."

When it comes to HUD's housing and community development programs, he armtwists and cajoles to enforce Section504 of the Rehabilitation Act for 1973, in effect, the Civil Rights Act for those disabled by multiple sclerosis, muscular dystrophy, myasthenia and polio, the paraplegics the quadraplegics, the blind, the deaf and the retarded. The legislation, which took effect last year, requires all institutions receiving federal money to remove obstacles preventing disabled persons from full participation in their programs - or face cutoff of the funds.

As director of HUD's Office of Independent Living for the Disabled, Williamson, 32, rides herd over department projects to assure barrier-free design: ramps instead of steps, lower elevator buttons, handrails in restrooms, doorways wide enough for wheelchairs. Get rid of the obstacle course, he says, and put the handicapped back into the mainstream where they belong, where they can enjoy life and contribute. Get them back into the mainstream, he says, and dry up the pity.

But legislating change is easier than erasing the "hearts-and-flowers poster child image" in society's mind, as he puts it. For one thing, the therapy establishment was slow to give up hte notion that the disabled could enjoy sports only as recreation.Only in recent years have disabled athletes begun to compete against each other on the grand scale of the Para-Olympics, where the creme de la creme face off.

Williamson the bureaucrat fuels the new image - Williamson the jock. He swaps the three-piece suit for the sweetshirt, pumps the triceps to exhoustion in events like the Boston Marathon and tries to get on the TV.

By now, he may well be celebrity. A film clip of his training rigors for the 26-mile race was aired on the Today Show and he also was bound for glory as a late-night guest in Tom Snyderland last week. He has plenty to talk about.

Last year, he won his Boston Marathon class in three hours and 20 minutes, and hour behind the winning runner, but well ahead of many in the fleet-footed crowd. And though he didn't fare as well this year - fifth in his class and 10th out of 18 wheelchair entrants - he felt he pushed a smarter, if (17 minutes) slower, race. He could no more avoid a busted axle 15 miles out than stop runners (and wheelchairs) from speeding on by.

"They passed me going uphill, but I passed them going downhill," he says. "Pushing 26 miles in a wheelchair is very respectable. The wheelchair weighs 40-45 pounds. An able-bodies runner gets to use the legs, but your legs are three times as strong as your arms. . .

"Losing builds character I'm told." But a brittleness in the voice betrays him. Williamson is a man who likes to win.

He has compiled a string of track and fiels cictories in official competition for the handicapped - 33 gold medals in the International Olympics, 22 gold medals in U.S. National Championships, 8 world records - since he caught polio at 6, one year before Dr. Jonas Salk developed the vaccine that has virtually wiped out the crippler.

In such competition, the handicapped are classed according to their disability. Polio destroyed the muscle tissue in Williamson's stomach and lower back, which affects his balance and ability to push. So he doesn't compete against, say, a paraplegic who lost his legs in Vietnam while retaining the use of the upper trunk muscles.

At the Toronto Para-Olympics in 1976, Williamson managed to heave the shotput 27 feet, the javelin 79 feet, the discus 90 feet. He whipped through the slalom event and pushed the 100-yard dash in 20.5 seconds to take home a silver and two bronze medals. The certificates hang in his office on the ninth floor of HUD's honeycombed beehive of concrete and glass, where, seated behind a desk, Dave Williamson, waist up, looks every inch the Olympic behemoth. He boasts 18-inch biceps and a 46-inch chest, hamhock forearms and a slim, 33-inch waist. People have been known to call him "Sir."

The adopted son of a surgical nurse and a high school custodian, Williamson was 14 when he met his benefactor - a crusty vet paralyzed in World War 11. The vet gave the Easter Seal Child from Evansville, 111., a "sport chair," a lightweight, armless wheelchair, and he entered his first race.

He envied friends their dancing, but claims his childhood was trauma-free. "You can't miss it if you haven't done it," he says. He kept records for his high school teams, got elected student body president, went on to graduate from Southern Illinois University, where he also took a master's degree and, circuitously, wound his way into government. Last June, HUD Secretary Pat Harris appointed Williamson OILD's first director. "I knew I couldn't make a living digging ditches," he says. "I had to rely on intellect."

And sports.

If you happen to be cruising Prince George's County one afternoon around Fox Hill Park, keep an eye out for a broad-shouldered, curly-haired fellow furiously pumping a wheelchair. That would likely be Williamson, who regularly straps weights to his chair and pushes a 5-mile course about the neighborhood.

He lives alone now, having recently separated from his wife who keeps their 3-year-old daughter. Physical disability, he says, did not prepare him for such a crisis in coping. "Sometimes," he quips, "I wish God would send me a memo."

He plans to keep pushing, though, lacking no modesty when it comes to self-image. "I'm an attractive male in a wheelchair. If a woman is interested in men of substance, she should consider meeting a man in a wheelchair . . .

"I think of myself and my wheelchair as one and the same. I keep it tidy and clean. I shine it like you'd shine a pair of shoes. I take pride in it. If a brick wall gets in my way, I go through it. That's the way I feel when I'm up, although that's not always the best way to be as a bureaucrat."

He brightens. "I was in Disneyland one time, just sitting there sunning myself and this little kid comes up and asks me, 'Hey, mister, are you a ride?' I said, 'That's right, kid. Hop abroad. That'll be 75 cents.'" That's a joke.

Watch out, Johnny Carson, here comes Dave Williamson.