WE CONCLUDED THAT a world-wide audience wanted more 'Jaws,'" declared David Brown, recalling the irresistible commercial impulse that led to the production of "Jaws 2," now in its first weekend of release at about 600 American theaters.

"In fact, our first choice for a title was 'More Jaws." Invariably, it provoked the same smile I see on your face right now."

Richard D. Zanuck, the other half of the smooth, symbiotic team of Zanuck & Brown, which once ran 20th Century-Fox under the chairmanship of Richard's illustrious father, Darryl F. Zanuck, and now operates as an independent production company based at Universal, nodded his agreement. "The studio does extensive market research," he said, "and though they suspected 'More Jaws' was facetious, they agreed to test it. The sample thought it was a joke too."

The partners made a brief stopover in Washington as part of a last-minute publicity blitz. Not that either partner felt apprehensive about the new film's chances. "One of the magazines referred to Universal's big gamble," Brown said, "but considering the expense of modern filmmaking, a sequel to a picture like 'Jaws' is really one of the safest investments imaginable.No one is operating in the dark. The studio had previews at about 30 places around the country last weekend, and the audience reactions seemed to be identical. They confirmed the studio's confidence.

"We did not want to be associated with anything shoddy or be accused of a rip-off. We never intended anything but a creditable sequel. As the producers of 'Jaws,' we had not only the privilege but also the legal option of producting it. We knew that if we declined, Universal would have had someone else there in a hurry. Perhaps you risk putting yourself at a disadvantage by trying to reprise a success of the magnitude of 'Jaws,' but our intent was a reprise with a difference, which we hope will satisfy those audiences who were pleased with the first film."

At 62, Brown is the elder member of the partnership by 19 years, and his courtly, avuncular manner, reminiscent of Walter Cronkite at his most reassuring. Although a Cronkite act-alike, Brown has a face that complicates resemblances pleasantly by making one think of Jack Albertson.

Brown probably made the same avuncular impression when he saw Zanuck's age, or even younger. Zanuck, on the other hand, appears destined to look youthful in a perpetually tanned, handsomely square-jawed way when he's as old as Brown. Although younger, shorter and less loquacious, he cannot be regarded as a junior or deferential partner.

Both men learned the film business under Darryl F. Zanuck's leadership, but the association began at the age of 36 for David Brown and at birth for Richard Zanuck. During their tenure together at Fox, Zanuck always held the senior positions, beginning as vice president in charge of production when his father returned to the company in 1962 and becoming president in 1969. In the same period Brown, who joined the company in 1952 as managing editor of the story department went from executive story editor to vice president in charge of creative affairs.

Both men received undergraduate degrees from Stanford. Brown also holds a Master's from the Columbia University School of Journalism. Before entering the movie business he worked for 13 years as journalist and editor. He was executive editor of Street and Smith Publications, the editor-in-chief of Liberty and the managing editor of Cosmopolitan. If Zanuck has a more famous father, Brown has a more famous wife - Helen Gurley Brown, who began as a secretary at Cosmopolitan and became its editor-in-chief.

Systematically exposed to the business when his father was the president of 20th Century-Fox from 1935 to 1955, Zanuck made his producing debut at the age of 24 with "Compulsion," the first and only success of the independent Darryl F. Zanuck Productions until "The Longest Day" came along. Before the return to Fox, the younger Zanuck also produced one total flop, "Sanctuary" and a modest hit, "The Chapman Report."

Zanuck had occasion to recall the latter when talking about the screenwriting credits on "Jaws 2." According to Zanuck, three writers made substantial contributions - Howard Sackler, who wrote the original screenplay; actress Dorothy Tristan, who revised it when her husband John Hancock was signed to direct; and Carl Gottlieb, who did rewrites after Hancock was dismissed after three weeks of shooting and replaced by Jeannot Szwarc.

"The credit went to arbitration at the Writers Guild," Zanuck said, "and only Gottlieb and Sackler get screen credit. I must say I was surprised. We submitted all three names, and Dorothy really suggested some key things, like the ending. There was no doubt all three wanted screen credit, which was a far cry from "The Chapman Report.' I had eight writers on that, and none of them wanted credit, although five did offer to use their pseudonyms.

"Sackler, by the way, never received sufficient credit for his work on 'Jaws.' He did rewrites for jusf four weeks and really didn't want a credit, but he did come up with the idea for killing off the shark, and he wrote Robert Shaw's long monologue about the sharks, which Robert then adapted and changed. I know John Milius has been taking credit for that speech, but his claim came as a total mystery to us, and it is still is. He is a friend of Steven's (Steven Spielberg, who directed both "The Sugarland Express" and "Jaws" for Zanuck and Brown), so maybe they discussed something among themselves. But we saw the pages of the script every day, and those particular pages came from Howard."

The Zanuck, Zanuck & Brown regime took over at Fox when the studio was reeling under the debts incurred by the interminable, profligate production of "Cleopatra." The comeback began with "The Longest Day," peaked with "The Sound of Music" and was sustained briefly with hits like "Valley of the Dolls," "Planet of the Apes," "Butch Cassidy and the Sundance Kid," "Patton," and "M A S H."

However, the saviours were sowing the seeds of their downfall at the same time by overrating the potential of such costly ventures as "Doctor Doolittle," "Start," "Hello, Dolly!" and "Tora! Tora! Tora!" Although "Dolly" did business, it didn't do enough to pay back its crippling production and interest costs. The others were emphatic flops, with or without exclamation points to rub it in.

Despite "Butch Cassidy," the studio reported losses of $25 million at the end of 1969. Despite "Patton" and "M A S H," it reported losses of $77 million at the end of 1970. That was the ball game, aggravated by a messy lateinning twist which found the elder Zanuck remaining as chairman for a time after acquiescing to demands from the board of directors that the younger Zanuck be removed from the presidency. Zanuck's position had been weakened even further during the summer of 1970 when he unwisely promised stockholders that such desperation attractions as "Myra Breckinridge" and "Beyond the Valley of the Dolls" would help turn the tide. On the contrary, they reinforced suspicion that the leadership was floundering.

Looking back, Zanuck says, "We let the success of The Sound of Music' go to our heads." Brown concurs: "We had to face the music. The production slate was our responsibility, and we had too much riding on too few pictures." However, sooner or later the system seems to luck out and backfire on everyone who succeeds in reaching a position of influence or authority.The track record of Zanuck and Brown illustrates how quickly shrewdies can look like saps and then shrewdies again with the space of a few years or productions.

After departing Fox, Zanuck and Brown set up their new production company at Warner Bros, where they immediately arranged a production they'd had to abandon at Fox, "Portnoy's Complaint." It bombed and soured relations at Warners. Switching to Universal, they began with exploitation fodder like "Sssssss" and "Willie Dynamite" before springing back to the top as the executive producers of "The Sting." Since then they've accumulated a representative backlog of respectable failures, disreputable hits, wipe-outs and smashes: "The Sugarland Express "MacArthur," "The Eiger Sanction," "The Black Windmill," "the Girl from Petrovka," "Jaws."

The producers themselves still confess to some mystification at the quiet failure of "The Sugarland Express" and overwhelming success of "The Sting," since they prefer the former and feel especially proud about encouraging Steven Spielberg's career. "Of course, we were closer to 'Sugarland,'" Brown said, "because we were the working producers on it, but we looked at each movie time and time again. 'Sugarland' always seemed fresh. There was something going on that you hadn't noticed before. With 'The Sting,' enjoyable as it was, you became awfully conscious of how long the takes were, of how long it took someone to cross the room and open a door."

Zanuck and Brown appeared to weather some confusion in their own mind about what "Jaws 2" should become. Their initial decision to hire Hancock as director seemed bizarre given his credits, none of which indicated an affinity for adventure or kinetic excitement - "Let's Scare Jessica to Death," "Bang the Drum Slowly" and "Baby Blue Marine."

"It may sound crazy," Zanuck said, "but I think the fact that John wasn't an obvious choice may have persuaded us that he could do it. We thought it might be another breakthrough, like Steven's. And there was no disagreement between us. We knew that John intended something on the Gothic, moody side. But when we saw how it was going to look on the screen . . . well, we were disappointed."

"John never deceived us," Brown added. "He was always straighforward about his intentions, and it sounded interesting. After three weeks of shooting, we simply convinced that it wouldn't work, that it wasn't what we wanted. So we closed down production at Martha's Vineyard and set about finding a new director before the bulk of the shooting, the seagoing scenes, which make up 70 percent of the film, was scheduled to begin at Navarre Beach in Northwestern Florida."

Is that when they contacted Spielberg? "No," said Zanuck. "Steven called us, absolutely out of the blue. He said that while he hadn't wanted to direct the sequel, he did have a large amount of pride and affection invested in 'Jaws,' so under the circumstances, he wanted to discuss the possibility of taking over."

"It might have been a lovely solution," Brown picked up, "but it just wasn't realistically possible. Steven had two months of post-production on 'Close Encounters' to complete. That was his estimate at the time. As it turned out, he needed even more time to finish polishing the film. We had to say this was impossible, because we couldn't postpone shooting until the following summer.

"Joe Alve, our production designer, who had worked on 'Sugarland' and 'Jaws' and 'Close Encounters,' for that matter, brought Jeannot Szwarc to our attention. In his TV days he had worked on 'Night Gallery," and three directors had impressed him - Steven, John Badham and Jeannot. We ran about 10 of Jeannot's TV shows, talked to the producers who'd worked with him, talked with Jeannot himself to get his ideas, and in effect we rolled the dice again. And, I'm sure, came up winners. He is a film aficionado of precisely the same kind as Steven. His life is film."

What about the film life of Zanuck & Brown? Do they plan to make a career of sequels to "Jaws"?

"We know of no plans at the moment to do a 'Jaws3,'" Brown said. "This is not like the James Bond series. How many times can you bring the shark back? Of course, we can't swear on a stack of Bibles that another sequel won't be made. Universal may desire one. They would have to come to us first. At the moment I haven't got a clue about what to do in another sequel."

The team has placed one large-scale project, a remake of "When Worlds Collide," on the back burner, owing to doubts about the immediate prospects of disaster epics. The projected "Continuation of Gone With the Wind" is "still struggling along," according to Brown, and will not be started until some writer (James Goldman is the present contender) submits a satisfying story. Asked if Goldman was being discouraged from following in the footsteps of his recent "Robin and Marrian," the producers replied in the affirmative.

"We do not envision Scarlett and Rhett ending up as poisoning victims in a sucidie pact"Zanuck firmly maintained. Let's hope not.