Moon Landrieu has a formidable temper, especially when someone questions his integrity.

According to the Metropolitan Crime Commission of New Orleans, for instance, there was a time in 1969 when he threatened to kill its executive director.

Now the secretary-designate of the Department of Housing and Urban Development, Landrieu says he can't remember just what he said, but he does recall that he was angry.

"Whether I said I'd choke the son of a so-and-so or punch him in the nose, I don't know," he said. "I freely confess to you that I was livid. I was livid."

The underlying dispute dealt with Landrieu's legal services for the TAC Amusement Co., the biggest pinball machine supply house in New Orleans at the time. TAC'S top officials, it later turned out, had been involved in cash payoffs to New Orleans police officers.

Landrieu, who was running his first campaign for mayor of New Orleans in 1969, has always protested that he was the victim of guilt by association. Federal prosecutors and investigators who handled the pinball bribery case, which came to trial in 1973, tend to agree.

Says former U.S. attorney Gerald J. Gallinghouse: "I can assure you that Moon Landrieu never participated in, and to the best of my knowledge, never condoned any violations of criminal laws by any client he represented."

But in New Orleans, rumors never die, and Landrieu, who still owns part of a shopping center in Jefferson Parish that grew out of his association with TAC, is anxious to knock them down before they spread to Washington.

His old antagonist, Aaron Kohn, now retired as executive director of the privately funded Crime Commission, still insists that there was a conflict of interest involved.

Chosen by President Carter as the new HUD secretary last month, Landrieu, 49, is now awaiting confirmation hearings, tentatively set to start Sept. 6 before the Senate Banking, Housing and Urban Affairs Committee. The committee already has started to dig into his financial affairs, and Landrieu seems resigned to some rigorous questioning.

"I've got a lot of enemies out there," he was quoted recently as saying. "You know, compared with college professors or long-time civil servants, mayors are bound to come into an office like this covered with barnacles."

Questions already have been raised concerning Landrieu's partnership interest in a multimillion-dollar New Orleans riverfront development seeking HUD funds and a Key West, Fla., hotel project that was approved for a HUD urban action grant the day before Carter named Landrieu to the Cabinet post. Landrieu has met those questions by announcing that he will divest himself of those holdings.

Of his connections with TAC, he says he simply wants to be judged by the standards prevailing in those days, rather than by the new post-Watergate restrictions on public officials regarding outside law practice and private sources of income. It is a favorite theme of his that if the government officials of 20 years ago were transported to today and subjected to present-day rules, "we'd all go to jail. I promise we'd all go to jail . . . . I can't win if anybody wants to measure me by today's standard, by rules which weren't yet thought of or written . . . ."

The Crime Commission controversy first cropped up at a press conference in September 1967 when Kohn, in response to questions, accused Landrieu of a conflict in continuing to serve as a lawyer for TAC while sitting on the City Council. The council was responsible for approving liquor licenses for the bars and restaurants TAC supplied with its machines, and not a few of New Orleans' watering holes were known to allow illegal pinball gambling.

Allegations that Landrieu had been labeled an "attorney for the mob" suddenly appeared in print. (Kohn says he called him an "attorney for an organized crime group," which somehow got freely translated.)

Landrieu was stung nonetheless.

Nobody had ever said anything like that about me before," he exclaimed in a lengthy interview this past week. "it was so ungodly unfair."

The peppery ex-mayor, who is given to somewhat Lincolnesque recollections, said TAC became one of his first steady clients a few months after he opened a walkup law office on South Broad Street in 1957.

"It had no air conditioning, no secretary, no books. Just me and a portable typewriter," he said. "I bought my furniture from Goodwill Industries right across the street and started practicing law. And I virtually starved to death."

One day, two men from TAC, which was started in 1932 by John (Tac) Elms Sr., came by to look at the empty storefronts downstairs. Landrieu says he struck up a conversation, invited them to use his phone and wound up with a promise of some of the amusement company's notary business, at 50 cents a signature.

Before long, Landrieu and two partners he took in, Pascal F. Calogero and Charles A. Kronlage, were processing liquor licenses ("part of the service" TAC performed for its customers), handling chattel mortgages for various bars and performing other chores. From time to time, Landrieu, who served from 1960 to 1965 in the state legislature, would go down to court to represent clients arrested on minor pinball gambling charges.

"We handled a lot of bar transfers over the period of time we were on Broad Street," Landrieu said. "And when you get to know bar owners by handling the transfers, one of the side benefits is that they up sending you business.

You know, a guy gets arrested in their place . . . Boom. Call Moon Landrieu. Or call Pascal. Or call Charlie."

As for TAC, "they became better and better clients," Landrieu said, but "we were never the principal attorneys for TAC Amusement Company . . . . I could tell you the [main] lawyers who were, but I get fearful that they'd get smeared. Two of 'em became federal judges."

Landrieu estimated that his law firm, which eventually moved into better quarters next to the TAC offices on Washington Avenue, never made more than $15,000 a year from the amusement company. But there were other benefits. A developer named William Gruber was putting up a shopping center in Jefferson Arish when he "ran out of money" and sought the help of Tac Elms.

"Tac sent him to us and said, 'See if you can help him,' " Landrieu recalled. "He said, 'You know, I don't mind investing if you all say it's okay, if you all take a piece. That was one of the ways Tac had, an intriguing way of protecting himself . . . . You put up your money, too."

The three law firm partners concluded it was a good investment, "did all of the legal work for free" and in January 1967 wound up owning one-third of the shopping center while Gruber kept a third and Tac Elms got the other third, Landrieu said.

"We put up dollar for dollar exactly what everybody else put up . . . in addition to the legal work," he said. "It may sound crazy, but that was the price we were charged to get in and that's what we did."

(Asked how much he put up, Landrieu said he couldn't remember, but he later said through a spokesman that his initial portion of the $600,000 price was $66,000. It was not clear whether this cost him anything. "He took out a loan," the spokesman said, adding that he had no other details.)

(Today, the shopping center, known as Continental Plaza, is turning a handsome profit. The only owners left, according to a spokesman for the HUD secretary-designate, are Pascal Calogero, Charles Kronlage and Moon Landrieu. Gruber sold out early.Landrieu stepped aside temporarily on being elected mayor to avoid any association with TAC. But then TAC bowed out, and Landrieu's old partners brought Landrieu back in. He now holds an undivided one-third interest.)

The Crime Commission dispute started in September 1967. Determined to bat down the conflict-of-interest charge, Landrieu says he told the commission he wanted a hearing and produced the records of about 15 cases in which he abstained from voting on liquor licenses for bars with which TAC did business.

"I can't tell you how righteous I was," Landrieu said, adding that he'd checked TAC'S purchasing records especially for the meeting and found that of the 18 Crime Commission members in the room, "I think 10 or 12 were doing business with TAC Amusement" by way of bank loans, equipment sales or other dealings. As for Kohn, Landrieu said, "some members of the committee, who were not friends of mine -- I didn't have one friend sitting on there -- began to shout at him: 'Aaron, tell him what he did wrong.' "

"The silence," said Landrieu, "was deafening."

Kohn has a different recollection. He sayd Landrieu did have "two friends" on the Crime Commission board "who did everything they could to get the board to deny me the right to speak . . . . They shouted at me to keep my mouth shut and not say anything. One of them told me his anger was because they'd already been trying quietly to build a mayoral campaign for [Landrieu]."

In any case, the commission issued a statement pronouncing its satisfaction that Landrieu's voting record "clearly indicates no evidence of the use of influence or a conflict of interest in these cases presented to it." The statement added that no one had called him an "attorney for the mob" and concluded with "regret that any recent publicity conveyed any impressions to the contrary."

Landrieu insists that Kohn concurred in the "apology," but to Landrieu's chagrin, the Crime Commission director gave a contrary impression to the TV cameras that night by refusing to comment, and he spoke out again about Landrieu and TAC in the months that followed.

The theme persisted into the 1969 campaign. Landrieu attempted to counter it by declaring that he would drop his law practice if elected mayor and by deciding to get out of the shopping center when that investment came to light. But all the while, he kept stating, as he told the New Orleans Times-Picayune that fall:

"I see no conflict of interest. I do not believe in pinball payoffs and neither does TAC Amusement."

According to Landrieu, Kohn had agreed in 1968, in the presence of New Orleans lawyer Cicero Sessions, "never" to mention Landrieu's connections with TAC again. Sessions disputes that. But no one disputes LANDRIEU'S threats of some form of physical violence the following year when "I heard that Kohn was saying it all over the city."

It was about three weeks before the final Dec. 13 runoff, and Landrieu conveyed his "harsh words" to the late Joseph W. Simon Jr., then executive vice president of the Chamber of Commerce and a member of the Crime Commission.

"So he [Simon] said, 'You want me to say that to the Crime Commission?' I said, 'tell 'em that. If they don't have any more decency that to permit this guy to go around maligning people after all I've been through, you know, then I don't have any use for the Crime Commission and I'll do my best to destroy it.' "

All that, Landrieu acknowledges, was a big mistake. He apologized to the Crime Commission Nov. 26.(He also disclosed his part ownership with Tac Elms and the others in the shopping center. The 1967 property transfer records contained no mention of his name although they mentioned everyone else.)

Kohn says he "didn't take the threat seriously," but silence ensued while the Crime Commission "agonized" over whether to break its traditional silence in political campaigns and share with the public this aspect of the leading candidate for mayor.

The commission bit the bullet three days before the election. The headlines are emblazoned in Landrieu's mind: "LANDRIEU THREATENS LIFE OF CRIME COMMISSION DIRECTOR."

I mean, banner headlines!" he exclaimed. "It was obviously the grossest political move that I'd ever seen any so-called civic board do." At most, he suggests, he might have punched Kohn in the nose. "And I would have been justified. I would have been justified."

Landrieu hurried over to the editorial offices of the Times-Picayune to seek redress which, he says, was granted with a front-page editorial denouncing the Crime Commission for "A LOW BLOW."

"Had it not been for that," Landrieu said, "I may well have lost the election."

Some four years later, Lawrence Lagarde, a partner in TAC Amusement, testified in federal court in New Orleans that he paid Joseph I. Giarrusso, then New Orleans police superintendent, $30,000 in six installments between 1968 and 1970 to protect illegal pinball gambling operations. He said ac Elms told him of the deal shortly before the senior Elms' death in September 1968.

Elms' son, John J. Elms Jr., another TAC partner, said at the same trial that the money was sent as stuffing in a box containing wine. (An Orleans Parish grand jury subsequently declined to indict Giarrusso.) The younger Elms said he learned of the arrangement after his father's death, when Lagarde told him.

But Elms also testified that TAC Amusement had never made any payoffs to Mayor Landrieu.

Adds a source who was close to the Organized Crime Strike Force investigation: "Moon came through. We couldn't find that he even got his nose dirty."