With their latest round of fighting just ended. North and South Yemen went through the motions of reconciliation today amid predictions that further clashes are likely within a matter of months.

Such gloom-particularly in the Arab world where reconciliation and renewed hostilities often follow each other with bewildering speed-is inherent in the longstanding and deepseated hatred dividing the two incompatible governments in Sanaa and Aden.

The North Yemeni president, Ali Abdullah Saleh, and the South Yemeni leader, Abdul Fattah Ismail, met in kuwait to discuss unification with the blessing of the Arab League, which earlier arranged a nominal cease-fire.

As one weary diplomat noted, however: "The two Yemens will never be united until one side wins and the other side loses."

A clear-out verdict between South Yemen, the Arab world's only avowedly Marxist state, and the pro-Western, more populars, but less united North is unlikely. There are enough outside actors-ranging from the Soviets and Cubans to the United States and Saudi Arabia to Arab League peacekeepers Syria and Iraq-to see to that.

With control of the Bab el-Mandeb strait guarding the Red Sea's entrance and the possible destabilization of Saaudi Arabia at stake, The Carter administration seized on the Yemen fighting to prove its determination to protect the Saudis, their allies in North Yemen and other conservative Arabs.

About $400 million is Saudi money is being pumped into supplies of American-manufactured tanks, armored personnel carriers, antitank weapons and a squadron of 12 F5E jet fighters to restore the fortunes of the badly bloodied North Yemeni military. $

"Caught with their pants down," in the view of one professional analyst, North Yemen's 19,000-man fighting force buckled under the terriifying impact of Soviet-built Stalin Organ missiles, heavy artillery, tanks and Mig-21s.

In retrospect, despite order provocations from both sides, the initial success should not have come as a surprise. The southerners had combat experience in Ethiopia's Ogaden and Eritrean campaigns, as well as Soviet and Cuban military advisers, better equipment and the element of surprise, sources here say.

Three Korean War-vintage Mig 17s-more than a third of Sanaa's operating combat aircraft-were hit by heatseeking missiles and a column of World War II-era T34 Soviet-built tanks broke down at the edge of the capital with overheated engines.

Eventually the Northerners found "courage and their second wind," the analyst noted, and fought back credibly. But recent army command shakeups clearly indicated the Sanaa government's displeasure with the initial showing.

South Yemeni regulars are back on their side of the border now, but their allies in the North Yemeni National Democratic Front announced Monday from Beirut that they will neither withdraw troops nor relinquish "liberated" territory.

In practice, they have allowed the Northern Army back into such key invasion route towns, as Harib in the east, Qatabah in the center and Al Besda in the west. But the Front claims to control a strip of mostly mountainous terrain estimated at between 20 and 30 miles in depth.

Thee South's original three-pronged attack on Feb. 24 seemed designed to use the approximately 500 Soviet and 350 Cuban military advisers reported in South Yemen to full advantage without risking them across the border.

The goal apparently was to seize key airstrips, interdict of cut roads leading from Sanaa to Taiz and Mokha and in general cut off the southern provinces in hopes of toppling the northern government.

he plan did not work, but getting rid of the Northern dissidents-who include followers of key disaffected Sanaa army officers-is likely to prove difficult.

Southern-based artillery still mounts sporadic barrages according to intelligence sources, and smallscale fighting between Northern troops and dissidents is expected.

The 32 American-made M60 tanks flown in from Saudi stockpiles-and the equal number en route by sea from the United States-are basically status symbols, although the North's obsolete armor proved no match for the South's more modern tanks.

"The best thing in this mountainous territory," a specialist said, "is a horse or a donkey."

The Saudis also flew in about 30 M113 armored personnel carriers from their inventroy. By year's end the northern inventory should include TOW and Dragon antitank wespons, M79 grenade launchers, 105-mm howitzers and other new American equipment.

American training teams numbering not more than 35 men at any one time are being dispatched on temporary duty of no more than two months to help the northerners use the new weaponry. A civillan-military team will come to train pilots and do basic maintenance on the jet fighters.

Although often illiterate, the Northern troops are credited with considerable mechanical skill. They basically lack leadership and discipline, however.

"These guys are a lot sharper than the California National Guard," one American training officer remarked.

Despite the Carter administration's well publicized-too well, in local eyes-decision to provide Sanaa with updated arms, only four American military men are stationed here permanently in addition to the military attache and Marine guards at the U. S. Embassy.

Northern concern over the Carter admininstration was based on squeamishness at being too readily identified with the United States at the time Washington was negotiating the Egyptian-israeli peace treaty and fears that such public trumpeting would encourage Aden to ask the Soviets for more weaponry in turn.