Carol Burnett has acted in "Love Letters" often enough that the popular drama's two-way correspondence might almost seem like an exchange of her own with a friend of long standing.

Someone like Brian Dennehy perhaps."I've done it many times - and this will be the second time with Brian," said Burnett, who will perform the play with him at Sundance. "We first did it at Telluride, oh, four years ago."

That earlier show was a benefit for Telluride's Sheridan Opera House. At 8 p.m. Monday and Tuesday, July 27 and 28, they will star in two performances of the A.R. Gurney play - the first night in the Sundance Screening Room and the following night on Sundance's outdoor Eccles Stage. This time proceeds will benefit Sundance Theatre's artistic programs, including the playwriting lab, the Sundance Children's Theatre Educational Tour, teacher-training workshops and related projects.

"Love Letters" gradually unveils the stories of a man and a woman through their revealing letters to one another, sent from childhood into adulthood.

This performance is being directed by Ted Weiant, who created an acclaimed Los Angeles production of the play that ultimately starred more than 250 celebrity actors. The cast's headliners were constantly shifting, with such notables as Charlton Heston, Sissy Spacek, Mel Gibson, Gena Rowlands, Ben Gazzara - and, yes, Carol Burnett and Brian Dennehy - among the revolving troupe of players.

Dennehy and Burnett separately took time out for telephone interviews to discuss their latest collaboration, and their links to Sundance.

"Love Letters," Burnett observed, "is funny - and it pulls the heartstrings too."

Which makes it an apt choice for both her and Dennehy.

Burnett is, of course, one of the funniest ladies on earth, famed for her long-running hit TV variety program, "The Carol Burnett Show," still seen in syndication, and a more recent recurring cameo as Helen Hunt's mother in "Mad About You" (which earned her yet another Emmy). Yet she's also an honored dramatic actress, praised for her work in such fare as the award-winning "Friendly Fire" and "Between Friends" with Elizabeth Taylor.

Dennehy has portrayed villains (he was Sylvester Stallone's persecutor in "First Blood," the first "Rambo" picture) and a big-hearted alien (in director Ron Howard's "Cocoon").

Burnett noted that she has been paired in the play with a range of accomplished actors, reading with the likes of Heston, Leslie Nielsen, Tony Roberts, Tom Selleck and Cliff Robertson as well as Dennehy.

Each of the actors, she said, brings to the male role different perspectives and virtues that she can react to.

"He's such a terrific actor," she said of Dennehy - one who can make you laugh one minute "and in the end he just breaks your heart."

Dennehy was equally generous.

"She's just one of our industry's icons," he said, "and there's nothing much more that you can say. She's one of the most enormously talented women of the 20th century. It's a privilege to be on stage with her."

When asked to appear at Sundance, "Love Letters" seemed a logical choice, the two said.

"We didn't have time to mount a big show or anything," Burnett said, "and `Love Letters' is so simple," requiring no scenery and very few props - just two desks and two chairs, side by side.

It's a popular choice among both actors and theatergoers, often generating memorable performances and striking a chord with audiences.

"We all have special relationships in our lives, which may or may not involve marriage or sex or commitment," Dennehy said. "In some cases they're the same gender - just a deep bond with someone who understands you when others don't. Performing this on stage, you can feel those moments when members of the audience open themselves up to it. It seems to be very much a shared experience."

Burnett's participation at Sundance this year goes even further, for she has written a script that will be one of eight projects being developed during the 1998 Sundance Theatre Laboratory.

Dennehy, who has carved out a wide-ranging career in film and television, said he enjoys getting back to his theatrical roots.

The actor has done a considerable amount of stage work in Chicago ("it's a very enthusiastic theater town," he said), including several projects with longtime colleague Robert Falls, artistic director of the Goodman Theatre.

Together, they've helmed a series of underproduced plays, such as "Touch of the Poet," "The Iceman Cometh" and "Galileo."

After "Love Letters" at Sundance, one of Dennehy's next Chicago projects will be a production that is definitely not obscure: a 50th anniversary staging of Arthur Miller's "Death of a Salesman."

"This was Miller's idea," said Dennehy.

Also in the works is a television miniseries based on a Tom Clancy work (being produced by the best-selling author), and Dennehy will direct a Showtime Western with a script by James Lee Barrett.

Carol Burnett is busy as well.

She just completed work in Toronto, where she's been filming "The Marrying Fool" for CBS. She stars in it with Walter Matthau, and the TV movie is being directed by Matthau's son, Charles.

In the fall she will be doing the Stephen Sondheim musical "Putting It Together" at the Mark Taper Forum in Los Angeles, "and then I'll be directing a play at my alma mater, UCLA."

That play will be "Once Upon a Mattress."

"I'll be going back to my old school, working with the kids on my old campus," she said - and doing the Broadway hit that helped make her a star 40 years ago.

"I've made kind of a big circle, haven't I?" she said.

- ALL RESERVED SEATS for Tuesday night's performance "Love Letters" on the outdoor Eccles Stage, which had been priced at $75 and $55, are sold out. There is still some limited, unreserved, lawn seating available, at $35 per person. For an additional $15, patrons may also attend a post-show reception in the Sundance Rehearsal Hall.

The additional Monday evening performance in the Screening room has just been announced. Seating is limited (150 persons). Tickets for this performance, combined with a reception, are $125 each. For reservations, call 1-801-328-3456 (ask for Joanna).

There will be no performance of this year's Sundance Summer Theatre production of "Gypsy" on the night of July 28.

Carol Burnett will also be a special guest at the annual Sundance Women's Series luncheon at noon on July 28 in the Tree Room Restaurant. Cost for this is $25 per person, with a portion of the profits going to a charity chosen by Burnett. Reservations are limited to the first 100 guests and can be made by calling Shauna at 1-801-223-4078.