There's still one place in Iran where they shout "Long Live the Shah" and mean it.

Eyes right at the reviewing stand, goose-stepping legs slamming down hard splattering the slush, the "Immortals" of the imperial guard strut their stuff to show they are very much around even if their beloved shah is not.

At a performance today on the snow-swept, asphalt parade ground -- as big as six football fields -- the shah was constantly in mind.

A giant portrait of the shah in uniform was hoisted aloft a 40-foot tower and his name was shouted, chanted and sung in unison by 1,200 soaked-to-the-skin "Immortals" of an all-professional brigade. The larger guard unit includes some conscripted enlisted men.

Just a week after the sovereign left Iran -- probably for good -- the "Immortals," in a prayer to God and an oath of allegiance, constantly referred to the shah as "his imperial majesty, shahinshah," or king of kings. Elsewhere, the deferential titles have fallen into contemptuous disuse, with most of the Iranian society grown accustomed to shouting, "Death to the shah."

Maj. Gen, Ali Neshat, the tall, erect, almost arrogant guards commander, gave visiting journalists the distinct impression that his unit meant business as usual.

And in the Shah's absence that meant defending the beleaguered consitutional government of Prime Minister Shahpour Bakhtiar against Avatollah Ruhollah Khomeini's efforts to replace the government and the monarchy with an Islamic republic.

"His majesty is on one of his regular vacations," the unsmiling white-haired general said as he held a silver-tipped swagger stick against the camouflage uniform worn by all the guards. "The troops see it that way. When his majesty comes back, my boys are all ready to shed their last drop of blood for him."

For the general, there was no question about whether the shah was returning, just when.

As for shedding blood, Hossein Amir-Sadeghi, a palace insider who organized the visit today, said that the day after shah left the "immortals" "nearly mutinied and went on the town."

"They would have killed a million people," Amir-Sadeghi said. The guards, he added,d "are their own men. This unit can take over the country on its own."

Amir-Sadeghi, the son of the shah's former chauffeur and a young man much given to verbal Exaggeration, had told journalists earlier that if Khomeini persisted in returning to Iran Friday as announced, senior officers, especially among the guards, "wanted to chop him up for dog meat or use him for target practice."

But today there was not the slightest suggestion of eroding discipline as the lean, fit, "Immortals" went throught their drill. They were paced by their 81-man ban, dressed in salmon and-gold-trimmed khaki uniforms.

All but forgotten was the incident last month in which one noncommissioned officer and an enlisted man, described as "communist agents," by Amir-Sadeghi. opened fire on the the officers' mess, killing 11 officers.

Today, an airborne unit opened the line of march as the guards goose-stepped for 30 seconds while saluting their commander and marking tribute to the shah -- their bayonets fixed, their heads erect under camouflage-netted helmets.

The rest of the drill involved climbing over obstacle courses, hoisting aloft the shah's portrait, operating Soviet-made mobile antiaircraft guns, showing off American recoilless rifles, mortars, armored personnel carriers and antitank weapons and British Chieftain tanks and, finally, demonstrating crowd control.

The inclement weather prevented a planned paratroop drop, but otherwise the "Immortals" made their point that they were a self-contained and ultraloyalist unit.

Amid the bristling weaponry and elitist esprit de corps, a more relfective colonel said, "Khomeini should come back from sitting in Paris and making inflamatory statements and getting people killed. He should come and see."

Asked where his allegiance now lay, the colonel said, "Bakhtiar is my boss."

And if, under the pressure of events, Bakhtiar were to be replaced by another prime minister, someone of Khomeini's persuasion, and no longer dedicated to the present constitution enshrining the monarchy, what would the "Immortals" do

With deliberate ambiquity, the officer replied, "We are ready."