The credits always call him James Stewart, but his fans know him as Jimmy, and so many moviegoers can't be wrong. He came to Hollywood in 1935, getting his start in a Spencer Tracy mystery. His career has flourished ever since, and though he's not as busy as he used to be, he still jumps at a good TV or movie role. He has even kept his zest for hitting the road and ''plugging a picture'' in the old Hollywood tradition.
In a switch, the pictures he plugged during his latest New York visit are in the neighborhood of 30 years old: a quintet of Alfred Hitchcock classics that have gone largely unseen since their first release, because the director felt rarity would increase their value. As it happens, Stewart stars in four of them, making their reissue (by Universal Pictures) as much a Stewart festival as a Hitchcock retrospective.
''Rear Window'' has already started its new run with strong results at the box office, indicating that viewers are still spellbound by the Stewart-Hitchcock chemistry. ''Vertigo,'' perhaps Hitchcock's greatest work, and ''Rope,'' one of his most rarely shown, will follow soon, along with the colorful 1956 version of ''The Man Who Knew Too Much.'' Also due is ''The Trouble With Harry,'' one of the suspense master's lighter and lesser efforts, sans the great Jimmy.
The New York Film Festival previewed ''Rear Window'' recently, and Stewart met the press afterward, admitting that he hadn't seen the picture for more than 20 years. Some of the conference focused on Donald Spoto's insightful new biography of Hitchcock, called ''The Dark Side of Genius,'' which claims Sir Alfred was a sadder, less balanced, more desperate man than most people have thought. Stewart took issue with this idea on the ground that ''if he had a dark side, it's not something he could have hid. And I just never saw it.''
The next day I drove with Stewart from his hotel to a Manhattan restaurant and enjoyed a long talk with him over lunch. Pressing for more details about Hitchcock and his work, I mentioned another Spoto theory - that Hitchcock used Cary Grant as an idealized version of himself, while Stewart represented the director as he felt he actually was.
It's a provocative notion, contrasting the glamorous Grant of ''To Catch a Thief,'' say, with the troubled Stewart of ''Vertigo.'' The actor wants nothing to do with such stuff, though. ''I can't help but feel this is overanalyzing,'' he says in the engaging drawl that's been his trademark for nearly five decades. ''There could be some truth and logic to it, but I've never felt that way, and Cary's never mentioned anything in that vein.'' In sum, he'll trust his instincts and recollections before the musings of critics.
Whatever the final verdict on Hitchcock's personality, Stewart speaks without hesitation about his ''tremendous admiration'' for the director, listing his own quartet of Hitchcock collaborations among his proudest achievements. ''The word genius is thrown around too much nowadays,'' he says, ''but I truly believe there are touches of it in his work. He had his own special way of getting on the screen what he'd prepared so carefully. He knew what he wanted. To be a part of this creation was a tremendous privilege. And a tremendous education.''
Stewart's show-biz ''education'' started young. He made his bow in a Boy Scout play and moved on to college shows. After graduating from Princeton University with an architecture degree, he joined such future luminaries as Margaret Sullavan and Henry Fonda in a theater group. Later he roomed with Fonda as they braved the Broadway scene and again when they hit Hollywood. Their careers were parallel to a degree, though today Stewart seems to have been the more expert actor, moving so easily from comedy to drama it's hard to say which mode suits him best.
During the 1940s, Stewart not only won an Oscar for ''The Philadelphia Story, '' but left the movies to fly bombing missions in World War II. He kept up his military connections after the war, becoming a brigadier general in the Air Force Reserve. Back on the set in the '50s, he struck up a long-term relationship with director Anthony Mann - and in the '60s, a similar one with John Ford.
As recently as the '70s, he reconquered Broadway with a revival of his hit ''Harvey'' and tried a couple of TV series with varying success. He's still at work today, appearing next month with Bette Davis in a cable-TV movie called ''Right of Way'' and preparing another project for early next year.
Of course, despite the versatility that has carried him through several media , Stewart is known mainly as the movie star who provided such memorable moments in pictures ranging from ''Mr. Smith Goes to Washington'' and ''The Spirit of St. Louis'' to ''Anatomy of a Murder'' and ''The Man Who Shot Liberty Valance.'' I asked if he's pleased that his career gravitated so strongly toward the screen instead of the stage.
''At this point in life, . . . when you start looking back,'' he replied, ''one of my regrets is that I didn't do more stage work. That's partly because it's a great, exhilarating, uplifting thing.
''But it's also because you never stop learning to act. It isn't that kind of a racket; you never have the thing licked. And the stage is great training for every part of it - timing, tempo, all your instincts about how to react without overdoing. . . . It's funny, but projecting your voice to the last person in the second gallery is wonderful training for movies, where you talk like we're talking now.''
Is there a typical Jimmy Stewart character? Stewart thinks there's something to the idea, as long as you don't push it too far. ''People have said - and I've felt it at times - there's a certain vulnerability about a lot of my characters. Perhaps this creeps into so many of my pictures because I've tended to select this type of character, because of my feelings about life.
''Even in a western, people say when I get in a fight they aren't sure if I'll win. But when John Wayne gets in a fight, they know, all right!''
He also feels his personal style - as a person and an actor - contributes to the notion of a ''typical'' Stewart character. ''And I see nothing wrong with that,'' he says. ''Someone asked Spencer Tracy if he got tired of playing himself all the time. He said, 'Who do you want me to play? Humphrey Bogart?' I feel it's all right to bring your own style to a character.''
Yet he stresses that acting is a demanding art that allows no free rides. ''People sometimes say they liked a performance because it was so natural,'' he remarks. ''Well, there's nothing more unnatural than movie acting. It's a craft that has to be learned, like any other.''
Looking at today's movie scene, Stewart feels there's too much ''sameness'' to pictures, both in theaters and on television. ''I don't believe in saying 'Give me the good old days' in anything,'' he muses, ''but I feel the old studio system was the best way to make movies. Whatever disparaging things have been written about them, the big moguls had tremendous love for the movies, and excellent judgement, and in a strange way, good taste. They didn't narrow themselves down. . . .''
Stewart is clearly nostalgic for the busy heyday of his career, when ''you had a contract and worked every day, including Saturday - and when you weren't in a picture you worked out at the gym or took diction lessons.'' But his enthusiasm goes beyond his own experiences. ''There was a period in the late '20 s and '30s and a little bit after the war,'' he says, ''when there was an exciting glamour about the movie business. It had to do with the stars and the studios and the MGM lion, roaring.
''I feel so fortunate I was a part of it. But I don't think it's here any more, and I don't know if it will ever return.''
With some 80 movies under his belt, does Stewart have a favorite? He answers quickly: ''It's a Wonderful Life,'' the story of a small-town banker who learns the significance of even the most unassuming person, directed by Frank Capra in 1946.
Does he value that film for more than technical or dramatic reasons? Does it reflect something of his own beliefs and ideals?
Stewart sits back and thinks for a moment. Then he answers, quietly and slowly, ''I think so. It might be a sentimental choice, being the first picture I made after the war, and knowing it's Frank's favorite, too. But it says some things that I think mean something to me. . . .''