Mario Andretti is inside his Pennsylvania office wearing the 1981 Indianapolis 500 championship ring. He slides it on his finger almost every day, way more than he ever wears the 1969 championship ring.

It's a matter of principle, he says.

The record books will forever say Andretti didn't win that race at Indianapolis Motor Speedway on May 24, 1981. Andretti says, defiantly, he did.

"I don’t care how you twist it or turn it," Andretti said Monday. "I'm wearing my '81 ring with pride because I know by the rule book I won that ring."

Bobby Unser, too, wears a 1981 Indianapolis 500 championship ring. The record books say he did win that race, his third Indy victory. Unser says there is no question the appeals panel got it right. And he received an even "prettier ring" when Andretti refused to give Unser the original ring back.

It was the most controversial finish in the Indy 500's storied history. Unser crossed the finish line first and was the unofficial winner. The next morning, Andretti was declared the victor. Five months later, after court proceedings, Unser was given the win back.

Andretti wouldn't give the ring back.

It was a feud like none other. Two of the biggest names in auto racing — the international star Andretti and America's racing prom king Unser — in a battle.

Before that race, Unser said he considered Andretti one of "the best friends he ever had" in auto racing.

"I was disappointed," Unser said Monday, "our friendship didn’t overcome that finish."

Andretti: 'I remember very vividly'

It was the last pit stop for Unser and Andretti and the race was under caution on Lap 149. When the two pulled out of the pits together, Andretti said he watched Unser pull off an illegal move.

By the rule book, which has the same rule today, if the field is alongside a driver coming out of the pits, that driver is supposed to look at the end of the wall and, whichever car he or she sees, blend in behind that car at Turn 2.

"I watched Bobby (pull out of the pits) and just accelerate to the front, right in front of the pace car," Andretti said. "I'm screaming to my guy on the radio, 'What the hell is going on?' Bobby went right up with the pace car."

The driver Andretti saw at the end of the wall as he pulled out of the pits was A.J. Foyt. Andretti passed a couple of cars, but then fell back. That left 11 cars between Unser and Andretti.

At race's end, Andretti crossed the finish line in second place. Unser was the winner.

Unser denies having done anything illegal.

"Everybody would like for me to say that the whole thing was Mario (should have won)," he said. "The truth of the matter is it is not."

He said he can prove his innocence.

"(Team owner) Roger (Penske) asked me after the race, 'Did anything happen? Anything different?'" Unser said. "I thought and thought and I said, 'What are you talking about?' He said, 'You didn’t have any close calls?' I said, 'No. Not a one.' I didn't know anything about it."

All he knew, Unser said, was that the race had been a breeze.

"I ran everybody all day. I kicked their butts all day long," he said. "All of them. It was a good day for me."

Unser was cheered as he shouted for joy in Victory Lane with a wreath of orchids around his shoulders and the Borg-Warner trophy behind him.

But later that night, as the rest of the country watched the race on television, the announcers said something as Unser pulled out of the pits. "Wait a minute. Unser can't do that."

'The race was done and run'

There was never any doubt for Andretti. He had planned to protest the finish. But at 5 the next morning, the usual time the official results were given out after judges worked all night to check the tapes, Andretti got a call: "Mario, you won the race."

Good, he thought, no protest needed. He went to the festivities at the winner's banquet. Had his picture taken as the 1981 champ, his second Indianapolis 500 win. And he was given the ring.

USAC officials had ultimately ruled that Unser had passed cars illegally while exiting the pit area. He was issued a one-position penalty. When official race results were posted, Unser dropped to second place.

"I was kind of (ticked off) they did that," Unser said. "After the race was done and run to switch the winner."

Unser and Penske weren't finished. They brought in a top sports lawyer from Philadelphia, who Andretti said "confused the situation, which was clear as daylight."

For months, depositions flowed. USAC agreed to have three outside judges make the final call.

Their decision in a 2-1 vote Oct. 9, 1981: Under the conditions, the penalty was too severe. Unser was fined $40,000 and reinstated as the winner.

Unser was up in the mountains in New Mexico when he learned he had been declared the winner. "The majority of the people thought we were right," he said.

At the 1982 prerace drivers' meeting, Andretti stood to ask race steward Tom Binford a question.

"Just to get it straight, any rule changes from last year?" he said. Binford replied there were not any.

"So, hypothetically, if I pass 11 cars coming out of a yellow flag from the pits, the fine is still $40,000?" Andretti said. No, Binford replied, according to Andretti.

"So the rule book applied that year, but not in 1981?" Andretti says now. "That’s the farce."

A friendship in question

The months-long battle had been high profile. People today may not realize the magnitude, said IndyCar broadcaster Jake Query. But this was a victory decision between the Yankees and Red Sox, the Celtics and Lakers, Ali and Frazier.

"There were no bigger names in sports at the time than those two," said Query, also the host of "Query & Schultz" on Fox Sports 97.5.

And the fact that the finish of that race ended in the two biggest names losing a friendship has always bothered Unser, though Andretti said it was more of a misunderstanding.

"Bobby was under the impression I was upset with him and mad at him all these years," Andretti said. "It’s not true. I never blamed Bobby or Roger Penske. I blamed USAC for allowing an outside force to come in and change the rule book."

Andretti has, over the years, gotten upset that Unser won't say he broke the rules.

When told that Unser said he was sad that the race had ruined their friendship, Andretti reiterated he didn't blame Unser.

"But all he had to do was say, 'OK. I got away with one,'" Andretti said. "And it would have been OK."

Follow IndyStar sports reporter Dana Benbow on Twitter: @DanaBenbow. Reach her via e-mail: dbenbow@indystar.com.