David James Elliott thinks his new NBC-TV show JAG can be just as successful and long-running as The Untouchables, where he starred as Paul Robbins, and programs like Doogie Howser, M.D. and Seinfeld, where he has been a guest star.

"There's absolutely nothing like JAG on TV now," Elliott says of the one-hour drama, which has drawn raves in its Saturday time slot.

The show takes place in the modern Navy, and producer Don (Quantum Leap) Bellisario takes pains to make sure it's realistic. Women star as officers and pilots. It 's about lawyers, the members of the Judge Advocate General's corps, but there is no courtroom action

"We take great pains to be current," says Elliott. "This is a lawyer show, but it's even more an action show."

Elliott spent months on pins and needles last winter waiting to learn whether he would get the starring role in the show, much anticipated because of Bellisario's past successes with shows like Quantum Leap.

"I can remember how many auditions there were," Elliott says while feeding his 2½-year-old daughter on a rare day off. "That's a tough routine, especially emotionally. You do stuff in one session and then three weeks later, they call you and ask you back and you try to remember what you did that they might have liked.

"So you try not to get too emotionally involved in any show. And that's hard, especially when they start talking about the money. You think, 'My God, what I could get with that,' and then you get all screwed up." But Elliott survived the process, and now he's into the next phase: Adjusting to life as the star of a one-hour drama.

"The schedule s absolutely brutal," he says. "We're talking 13-hour days, with a make-up call usually at 6 a.m. and I don't get home 'til 8 every night. And the work can be hard when you're in absolutely every scene." But the show - and the fact he's working - makes all that worthwhile, Elliott says.

"I've seen some really lean times," he says. "There was one year when I auditioned for a soap opera in New York and they put me on hold and then the deal fell through. Then I was going to be in a play and the money disappeared just before it opened. Finally, the soap called back and I turned down a role in another play. Then the soap called again and said 'no' for keeps this time." After that, Elliott was jobless for a year, ending up a guest on the couch of his dad's apartment in Toronto.

But then he landed a job as a cop on a Canadian TV series called Street Legal, and his career took off. There were guest shots on Doogie Howser, M.D., China Beach, Knots Landing and Melrose Place. There was a gig as the alcoholic second husband of Michele Lee in the CBS TV movie The Dottie West Story.

If Elliott has one wish about JAG it would be that the Navy eventually cooperates more closely with the show. The show's two-hour pilot episode was set aboard an aircraft carrier, but the crew was forced to work aboard the mothballed USS Lexington, docked in Corpus Christi, Texas, because the Navy wouldn't allow access to an active ship. The pilot show probably didn't please the Navy.

It featured plenty of male-female friction, with a woman radar intercept operator being pushed overboard from a carrier, and the ship's captain none too anxious for a thorough investigation.