They'd often walked that street before, but it always stayed beneath their feet before. Now the Firestones, Bert and Diana, fairly floated over the back streets of Belmont Park. Their filly, Genuine Risk, had finished second in the Belmont Stakes, and when Diana Firestone saw a friend, she cried out from a distance, "Wasn't it wonderful!" f

"She tried her heart out," Bert Firestone said. In disputed defeat at the Preakness, darkness owned Firestone. This time he was aglow with joy. "What a super filly," he said. "We couldn't be happier."

"You could be happier," someone said.

"A little but, but not much," Firestone said, his face positively beatific.

So one of thoroughbred racing's nice stories came to a touching end today when Genuine Risk not only becamse the first filly to run in all three of the Triple Crown classics but ban strongly and courageously. Winner of the Kentucky Derby, second in the Preakness and second here, Genuine Risk is the best 3-year-old in America.

LeRoy Jolley says so.

"Consistently she is the best," said the filly's trainer, whose horses have won two Kentucky Derbies and three Eclipse awards. "Regardless of the conditions, she runs her race. It takes a new colt to beat her every time."

Condex won the Preakness when the Pimloco stewards grew weak in the knees at the thought of calling an obvious foul. Angel Cordero, the jockey on Codex, ran wide through the turn for home and interrupted Genuine Risk's move to pass. A fould claim by Genuine Risk's rider, Jacinto Vasquez, was dissallowed -- first by the stewards, then by the Maryland Racing Commission.

A horse that paid $108.80 on a $2 bet, a nonentity called Temperence Hill, won the Belmont today. He did it in a duel down the homestretch with Genuine Risk and Rockhill Native, who fell back to third. The money will spend, the $176,220 to the winner, but the glory will go to the chestnut filly who took hold of America's heart for six wonderful weeks.

She astonished us in Louisville, as the first filly to win the Derby in 65 years. We ached for her in Baltimore, where she was done wrong. Here she had the worst of it -- pinned by other horses to the inside of the race track, always the slowest part here, especially on a track made muddy by an overnight rain -- and yet here she came at the end, her copper coat splattered with mud, the white blaze somehow shining, the rider Vasquez whipping left-handed, asking for everything she had.

"My filly, she was running as hard as she can run," said Vasquez, who said his war of words with Cordero -- he threatened to pull his old friend off Codex in midflight if he interfered again -- produced no incidents today and is over.

"She eat a lot of mud on the backside, and that didn't help too much," Vasquez said. "To run a mile and a quarter behind the mud, she has to be a real tough horse, to love the mud. An eighth of a mile to go. I was riding her real hard. She trying very hard. My filly, she try until the last 16th. She kind of stop then."

Not so you'd notice. If anyone stopped, it was Codex. Codex finished seventh, 7 3/4 lengths behind Genuine Risk. As rudeness was the Cordero modus operandi in the Preakness, rationalization was today's program.

The mud beat him.

The mud.

The same mud that Temperance Hill ran in.

The mud Genuine Risk ate.

"I'd love to have another race with the filly," Cordero said, adding, "under better conditions."

In January, Codex twice ran poorly in the slop. But by the first turn today, it was clear Codex was not sliding in the mud. It is a test of class to run in all conditions, as Jolley said so pointedly, and today Codex failed that test.

The Preakness "winner" failed another test, too. He always had run under the influence of the drugs Butazolidin and Lasix. Bute is an anti-inflammatory drug that reduces pain, and Lasix is said to stop the spontaneous bleeding that strikes horses during a race. These drugs are outlawed in New York, and Codex raced cold turkey.

Someone asked Jolley if today's second-place finish, with Codex far in arrears, was particularly satisfying.

"Yes. Here in New York, we run on hay, oats and water," he said. "That's the way it ought to be all over the country.

Take that, Codex.

"They got excuses," Vasquez said. "The race track today, muddy. Always excuses on the race track. They didn't like the track, or they didn't eat the night before. Always excuses.

Genuine Risk's rider isn't buying the excuses.

"My filly the best 3-year-old," he said. "She's the only 3-year-old to make all the Triple Crown races, and she did well. This year I don't see anybody else better than she is. The race she ran in Kentucky, no funny race."

It is a killing challenge, these Triple Crown races. Jolley, after his filly finished third in the Wood Memorial two weeks before the Derby, didn't want to risk her in a series so exhausting that big, strong colts have passed it up.

But Bert Firestone wanted to try. He had come close in the Derby with Honest Pleasure, finishing second as the odds-on favorite in 1976, and again last year with General Assembly, also a runner-up. The filly was special. She had a chance. When he saw the Derby Field would be 10 or 12 horses and not the expected dangerous stampede of 20, Firestone sent Genuine Risk to Kentucky.

She won the Derby with a long, dramatic move on the last turn, passing three big, strong colts. She might have won the Preakness except for Cordero's insistence that ladies belong a step behind. For most of the mile and a half of the Belmont today, Genuine Risk was trapped on the rail until Vasquez moved her up in a small hole between horses going into the last turn.

At the top of the stretch, Genuine Risk was the leader.

"They squeeze me a little on the back side, but it didn't cause me any trouble," Vasquez said. "But when Temperence Hill came, nothing I could do."

On the back side of Belmont Park, the Firestones walked down a street of dirt and dust, pebbles and asphalt. They walked where horses had walked. They walked in wonder. "Now we're going to rest her for a while, three weeks or so, and freshen her up for Saratoga," Firestone said, referring to the meeting that starts there in August.

Would the filly now run with fillies or continue against colts?

"Wherever we have the best shot," Firestone said. "We'll probably go with fillies now. But, really, it's all up to LeRoy. Whatever he wants to do."

Firestone said he probably was done with his appeal of the Preakness ruling. There had been talk he would take the issue to court. "We've made our point," he said. "The rules said we could appeal to the commission, and we did. To do anything else, we'd have to go outside the system and we don't want to do that."

Diana Firestone suddenly shouted, "There she is!"

The filly, Genuine Risk, had walked out of an examination barn and was turning a corner 100 yards away.

In her classy blue dress and elegant red hat, Diana Firestone, a woman in love, ran down the dirty street to be with the filly.