As U.S. and Panamanian negotiators work around the clock to conclude a long-awaited new canal agreement, Americans and Panamanians here are beginning to adjust to the idea that their 70-year relationship is about to change drastically.

Both Americans in the Canal Zone and Panamanians had become used to disbelieving that a new treaty could come about after watching 13 years of, so far, inconclusive talks.

But as negotiators on both sides are still hoping for a Wednesday or Thursday signing ceremony, American and Panamanian residents are in inevitably opposite frames of mind.

For 1.7 million Panamanians, the future promises a national celebration, a rain of dollars and the eventual takeover of the U.S.-built "path between the seas."

But the 13,500 U.S. civilians who were eith born or acclimatized to life on this narrow strip of tropical U.S.A. face the prospect of losing what they were once so sure of: their U.S. laws, U.S. produce and, worst of all perhaps, their jobs.

While skeptics on either side are still holding out with an "I won't believe it until I see it" attitude, political circles in Panama City are becoming excited over the impending news.

"We talk of nothing else, it's very very exciting," saia a Panamanian civil servant. "We're only worried our government had to give in too much. Washington knows how desperate we are for an agreement."

By the canal locks at Pedro Miguel, an American Canal Company employee watched the water level rise against the giant doors and shrugged. "I guess we are just about resigned to whatever may come," he said. "Just don't print my name because we're a little tense around here. We don't really know that to expect from them."

By "them" he meant Panama's left-wing, nationalist student groups that in the past have caused riots over the canal issue. This morning word was spreading among anxious Zonians that the students were "up to something," like a triumphant march into the zone when or if the agreement comes.

One student group, the Socialist Revolutionary League, today produced a statement denouncing the government of Gen. Omar Torrijos for accepting only a "possible" but not a "just" treaty. However, this group and others that were contacted said they had no plans for any march into the zone.

Panama's press, which ordinarily gives little time or space to voices of opposition, is showing the first sign that a national debate the plebiscite required to ratify a draft treaty. Several letters and speeches from the so-called Movement of Independent Attorneys, of a mixed ideological bag, have been published in which they chide the government for its secrecy during the talks.