CBS News announced yesterday that Dan Rather will succeed Walter Cronkite as anchor and managing editor of the CBS Evening News sometime between February and June of next year.

Rather will continue as a correspondent for "60 Minutes" for the time being but will begin "immediately" to substitute on a regular basis for Cronkite whenever the latter is on vacation or assignments, as part of the "breaking-in" process.

Neither the length of Rather's "long-term contract" as anchor nor his salary as the replacement for the nation's number-one newsman was disclosed at a press conference held yesterday in New York by Rather, Cronkite and CBS News president William Leonard.

Other sources indicated yesterday that Rather's salary will be in the range of $800,000 a year, which reportedly just about matches Cronkite's yearly stipend at CBS News, although the published figure for Cronkite is usually pegged at about $650,000.

In addition to the anchor job, Rather will inherit Cronkite's election-night and national-convention anchor chores when he takes over.

The precise date of the changeover is not set, but Cronkite said yesterday that it would definitely be after the January 1981 presidential inauguration.

"I've inaugurated every president since Harry Truman. I want to inaugurate one more," Cronkite said. A June changeover would coincide with the time Cronkite usually begins his summer vacation.

Yesterday's announcement that Rather had been chosen to succeed Cronkite came after at least six weeks of intense negotiation between Rather and CBS News and only after Cronkite had cleared the way for the orderly succession by convincing CBS executives he really did want to leave "the daily grind" of anchoring the Evening News even before the end of his current contract in November 1981 -- a suggestion that they had had understandably chosen not to take seriously in the past, given Cronkite's unique popularity in American news.

As the chronology was pieced together from several sources yesterday, Rather was told more than six months ago that Washington correspondent (and substitute Cronkite anchor) Roger Mudd was in line to succeed Cronkite.

About six months before that, CBS News executives and CBS Broadcast Group president Gene Jankowski had begun informal talks about the problem of replacing Cronkite if and when the premier anchor chose on his own to step down.

There was no urgency in the talks, and at one time last fall Mudd himself was told that perhaps a double-anchor composed of himself and Rather might be a solution whenever the dreaded day of Cronkite's pullout occurred.

Meanwhile, Rather's agent, Richard Liebner, let it be known that his client might be available, and sometime last fall ABC News president Roone Arledge offered what has been called "a very attractive package" to Rather.

Rather, in turn was personally "very impressed" by Arledge and his long-range plans to build a journalistically sound ABC News -- which already is successfully challenging second-place NBC News in the ratings.

According to sources, Arledge did not make an extravagant money offer to Rather, despite published reports that something like $8 million in five years was on the table. Instead, he reportedly appealed to Rather's pride as a contributing news executive.

In December, Liebner and Rather informed CBS of the ABC offer.

From the start, Rather was torn between his "head" which told him to accept that ABC bid, and his "heart," which told him to stick with CBS after 18 years and some of the best assignments in TV journalism -- including the assassination of President Kennedy, Vietnam, the White House and chief anchor of CBS Reports and the high-ranking "60 Minutes."

Moreover, Rather welcomed a chance to replace his idol Cronkite, but only so long as the change in no way forced the latter to leave early. It was Cronkite, after all, who had stuck up for Rather at CBS News when he had been criticized from several quarters during his coverage of the Nixon White House.

With Cronkite's announcement last week that he wanted to leave the anchor spot on the Evening News to focus on his new "Universe" science series anchor chores and a variety of documentary, special event and hard-news assignments away from the "daily grind," Rather was forced to make a decision. a

He reportedly spent most of Wednesday agonizing over the choice between ABC and CBS and notified both yesterday morning of his decision.

News president Bill Leonard immediately flew to the CBS News bureau in Washington to inform Mudd of their choice.

Leonard said yesterday that "we began [the meeting] with a handshake and we ended with a handshake."

Leonard told the press conference yesterday that "if I had a wish remaining in this world . . . it would be that Roger would continue with Cbs . . . he's very important to us, he's very much one of a kind."

Rather added that "Roger Mudd is one of the great reporters of my time. He's a very good friend of mine."

And Cronkite said that "I think it would be a tragedy for us and CBS News if we lost Roger MUDD."

Mudd, whose current contract with the network runs out at the end of this year, issued a statement later in the day but otherwise refused to talk to the press concerning the CBS decision.

"The management of CBS and CBS News," Mudd's statement said, "has made its decision on Walter Cronkite's successor, according to its current values and standards. From the beginning, I've regarded myself as a news reporter, not as a newsmaker or celebrity."

Asked at the press conference what made him choose Rather over Mudd, Leonard said yesterday: "It was a very, very close call," and cited "Dan's extraordinary experience" from Vietnam, to civil rights, to the White House, to chief of the London bureau.

Sources at CBS have indicated that Mudd's dedication to his beat on the Hill to the point of sometimes refusing other assignments over the years did, in fact, weigh in the balance when the decision was finally made.

Leonard said yesterday that the decision to choose Rather was his, which he "shared with a few close colleagues in the news division" and (in a decision this important) with Broadcast Group president Jankowski, Cbs Inc. president John Backe and CBS Board Chairman William S. Paley.

Other sources suggest that Jankowski and Backe, on hearing in December that Rather was seriously considering ABC, issued strict orders to Leonard not to lose either Rather or Mudd in future negotiations, confronted, as CBS News suddenly was, with the sudden possibility of losing three top people, including Cronkite, who were considered keys to CBS News' 10-year reign at the top of the news ratings.

Meanwhile, there have been numerous reports that both NBC News, now run by ex-CBS News executive (and close friend) Bill Small and Abc News have made overtures to Mudd, who has long been considered one of the top TV newsmen in the business.

As for Rather, he was asked yesterday if he would have stayed at CBS if he didn't get the job.

"Yes," he said. And of the offer he had recieved from ABC News? "I listened. I considered them very seriously." He added that in the final consideration, "CBS is a team . . . a family."

He also said that "i'm a line reporter. That's what I wanted to be and that's what I'll continue to be to the best of my ability" in the tradition of Walter Cronkite and Edward R. Murrow.

He was "humbled" to be chosen, first, because "there are a lot of people at CBS News who could do the job"; second, because "everything funnels into that symbol [the man in the anchorman chair] the whole effort"; and third, because "I know how many times I've failed to do the best job I can."

And so Dan Rather, once informed he was out of the running, and not longtime heir apparent Roger Mudd, yesterday at 3:30 p.m. was signed to a contract by CBS News to take over the number-one anchor job in television. a