Thailand's new strong man is also nation's Mr. Clean

The choice of Gen. Prem Tinsulanonda as Thailand's new Prime Minister by the nations's two houses of parliament has assured a smooth transfer of power without the disruption of an Army coup.

The pledge of cooperation with the new government by Kukrit Pramoj, leader of the Social Action Party, the largest opposition group, is a further guarantee of at least short- term stability.

But the new leadership following last week's resignation by former Premier Kriangsak Chamanan still casts a questionmark over the country's future, especially in the critical area of foreign policy.

For even slight differences in direction by the new leadership could affect relations with Vietnam over the sensitive question of Thailand's border with Cambodia.

Under General Kriangsak Thailand was working to avoid a confrontation with Vietnam that might have brought Vietnamese troops pursuing Khmer Rouge guerrillas into Thailand.

Another major danger was that Vietnamese operations in Cambodia would push hundreds oif thousands more Cambodian refugees into Thailand.

Nonetheless a high degree of continuity is generally expected from Thailand's new ruler, a bachelor who once declared he was "married" to the Army. One reason is that the power of national bureaucracy and local officials is extremely great in Thailand, so that in many kinds of policies who is at the top makes little difference.

According to some sources the secret vote by both houses of parliament gave the general a total of compared with & for Kukrit Pramoj, the runnerup. Other candidates received only a handful of votes.

There was some expectation that General Prem would seek economic expertise from Kukrit Pramoj's Social Action Party in staffing his new government.

But in telling reporters that there would be no coalition between the government and his party, Mr. Kukrit made it clear that his pledge of cooperation may have its limits.

General Kriangsak's decision to resign insured that there would be no military coup, a frequent means of transferring power in Thai politics. If there is large-scale popular discontent, Army factions often plot to mobilize this by overthrowing the current leader.

In this instance there was discontent both within and without the Kriangsak government. Last month's oil and electricity price hikes were unpopular with the public, tarnishing General kriangsak's popularity. Opposition parties were increasingly outspoken in their criticism and pushed for a vote of no confidence.

General Prem, formerly defense minister, can now proceed with the unpopular price hikes behind him, unblemished with blame for being the instigator.

He begins his term in office with a reputation for incorruptibility that is unusually strong for Thai generals and politicians.

As a longtime leader of his country's campaign against communist guerrillas, he is likely to bring to office a strong sense of what must be done to keep the insurgency in check.