What an anniversary present -- 108 long-awaited U.S. tanks and a warm message of congratulations to go with them from the president of the United States.

"Morocco is very happy," said Moroccan Ambassador Ali Bengelloun, glowing with excitement last night at a jampacked national day reception celebrating King Hassan II's 20th anniversary on the throne and the 25th anniversary of Moroccan independence.

The Moroccan ambassador -- to say nothing at all of his king - has been waiting months to hear whether the United States would sell the pro-Western North African country $182 million worth of Patton tanks. Then yesterday, with the kind of timing that hardly seemed coincidental on an occasion so important to Morocco as its national day, the Reagan administration notified Congress that it was ready to go ahead with the sale.

By last night, in a turnout that would have rivaled an Iranian Embassy national day in its pre-Khomeini days, hundreds of Morocco's old and new friends climbed out of their limousines at the Bengelloun's embassy residence in Cleveland Park to rejoice over roast veal, spiced shrimp, couscous and an assortment of fresh fruit straight from the Arabian nights.

That meant a stellar cast headed by Speaker of the House Thomas P. (Tip) O'Neill, former secretary of state Henry Kissinger, Attorney General William French Smith, HUD Secretary Samuel R. Pierce Jr., Commerce Secretary Malcolm Baldridge, national security adviser Richard Allen, the ambassadors of several dozen foreign countries, countless Washington lobbyists, attorneys, consultants, think-tank types, journalists, socialites, military attaches and just about anybody else who ever took -- or wanted to take -- the fabled road to Morocco.

If Morocco's war in the Western Sahara against Polisario Front guerrillas was a topic under discussion in some groups, in others was the Reagan administration's decision to send military advisers and hardware to El Salvador.

Kissinger, who knew plenty about both and what they can lead to, said he and Reagan talked about El Salvador "in general terms" before the inauguration. But he claimed he saw no analogy between it and Vietnam.

"Not at all a comparable situation," he said.

On Soviet leader Leonid Brezhnev's suggestion for a summit talk, Kissinger said that while he was in favor of negotiations he thought they should be conducted at the "lower levels" first.

"I think it's bad to start negotiations at a summit," he said.

Looking like he just got back from Acapulco ("We just got back from Acapulco," said Nancy Kissinger), Kissinger hailed Speaker O'Neill, who was making a rare appearance on Embassy Row, with some long-time-no-see camaraderie.

"You've lost some weight," said Kissinger, looking particularly fit himself after a month of daily handball.

"I'm heavier that I ever was," lamented O'Neill.

When someone asked him how the Democrats were doing these days, he paused in midpath.

"Everything is right on schedule," he said, looking his questioner straight in the eye. "We've given them [the administration] a schedule and we don't intend to deviate and we don't intend to obstruct."

The place was crammed with power players from the past:

Outgoing ambassador to Morocco Angier Biddle Duke, still on the payroll for a couple of days, in town to testify on U.S. policy in North Africa until the committee chairman was sent to Korea; former assistant secretary of state Harold H. Saunders, writing a "forward-looking" book about the challenge to American interests in the Middle East in the 1980s; former undersecretary of state David D. Newsom, "just enjoying myself completely" at the Georgetown University School of Foreign Service; former chief of protocol Abelardo Valdez, now practicing law, and another former protocol chief, Kit Dobelle, "catching my breath for the first time in four years."

Power players straight from the present included Chinese Ambassador Chai Zemin, Saudi Arabian Ambassador Faisal Alhegelan and, in the absence of Soviet Ambassador Anatoliy Dobrynin, Soviet military attache Maj. Gen. Vasiliy Chitov, bringing news of Brezhnev's reelection as head of the Soviet Communist Party. And also that the next step after cold war is real war.

The new Chief of Protocol-designate, Leonore Annenberg, deciding the Moroccan party was "a good place to start," said it reminded her of the good old days in London when her husband was the U.S. ambassador. "It's like starting all over again."

Setting a time limit for herself, she left promptly after 20 minutes. Others were less disciplined.

"The Moroccans throw a darling party," moaned one guest, "but they do try to cram in too many people."