Barbara Walters and Katharine Hepburn -- what a fabulous coupla babes -- meet again tonight on the season premiere of "20/20," the successful ABC News magazine that ABC executives have thoughtlessly dumped onto the Friday night schedule after eight of its 10 on-air years as a Thursday night fixture.

It airs at 10 on Channel 7. In addition to the Hepburn segment, there will be an investigative piece on the hazards of disposable lighters, and a report from the Philippines, where American servicemen are contracting AIDS from Filipino women.

Friday is considered a very poor night to air informational programming. Booking a star like Hepburn may help lure viewers to "20/20," and this interview is pretty good, although it comes at you in little parcels, interspersed with film clips and too much Walters narration. There isn't enough continuous, sustained conversation.

The spotty approach may have been dictated by an overanxious producer (and believe me, 95 percent of them are overanxious) or it may be because Hepburn, in her advanced years, seems to talk only in short little bursts. Walters barges right in there, though, and asks Hepburn something we've all wanted her asked, why it is that her head shakes so.

Hepburn, not offended by the question, says she does not have Parkinson's disease, which can cause a similar kind of symptom. "It's from my grandfather Hepburn, who was a minister," Hepburn says. "His hand shook . . . and his head shook . . . If you drink enough whiskey, you can stop that."

This is fine, but then Walters in her voice-over narration says, "From her grandpa, she inherited the shakes." Well, somehow, "the shakes" sounds a little insensitive. Walters often draws the line at the wrong place. But she is nothing if not brave. She asks Hepburn about her long affair with Spencer Tracy, whom Hepburn discusses here in more detail than she will usually allow.

Hepburn ended a PBS tribute to Tracy last year with an embarrassing letter to Spence in Heaven that she had composed. Her devotion to him seems more touching as expressed in answers to Walters' questions. "He was funny. He was witty. He was delightful company," Hepburn says. "A most entertaining fellow."

Some people, including interviewers, treat Hepburn like a living saint. It gets gooey. Walters doesn't go overboard in the worship department. But she cheats a little when recalling their last interview together, for a "Barbara Walters Special" that aired in June of 1981. That was the interview that started all the jokes about Walters asking people what kind of tree they would like to be.

What actually happened, Walters says, is that Hepburn volunteered the remark, comparing herself to an old oak tree. Walters says, "Everybody laughed at us, remember?" No we don't remember. Everybody laughed at her -- not at them.

For all her fame and inestimable wealth, Walters still appears to work hard at these interviews. She applied the forceps and pliers trying to get something out of Fawn Hall the other night; but Fawn was a naughty girl and wouldn't say diddly. Hepburn is a far worthier subject. And even, at 78, more beautiful.

So, what becomes a legend most? Why, an interview with Barbara Walters, of course.