Three days a week David Thebehali sits in his second-floor office in this segregated black township outside Johannesburg, dispensing patronage and advice to some of its desperate citizens who line up outside his open door.

On a recent Friday, more than 70 people were waiting. There were quarreling couples and abandoned women, a man in a flashy tie and dark glasses who wanted a peek at his official file for some dubious-sounding transaction and another complaining that his wife had not slept with him for three years.

Some sobbed as they told their tales. One fell in a shrieking fit on the floor.

As chairman of Soweto's Community Council, effectively its mayor, whose powers are exercised through the white government apparatus, Thebehali is lawyer, landlord, arbiter of business rights, magistrate and "Mr. Fixit" for the million people who live here under the system of impermanence imposed by the segregationist policy called apartheid.

No black person can own property here. They can only rent, and Thebehali controls the rents.

He is a soft-spoken man with a gentle smile and appears genuinely concerned about the welfare of those endless streams of people who file into his office.

But Thebehali is not popular. Many of Soweto's inhabitants see him much as people in an occupied country view fellow residents who serve an enemy administration. The differing attitudes of blacks like Thebehali who work within the apartheid system and those who fight to overthrow it illustrate the many issues dividing South Africa's 19 million blacks.

Although the blacks form the great majority of the population, they have no voice in governing the country.

"The man is beyond the pale, the ultimate stooge," says Dr. Nthato Motlana, chairman of Soweto's Committee of 10 who rose to prominence in the Soweto uprising in 1976.

In the Community Council elections that followed the upheaval, only 6 percent of the electorate voted and Thebehali got 96 votes. Motlana's committee boycotted the poll. New elections were due last year, but the government has postponed them twice.

Meanwhile, Thebahali has just moved into a $100,000 house given to him by an Afrikaner business concern. His Community Council offices are surrounded by a high security fence, and the grounds are patrolled by a guard with a shotgun. His official car was damaged by a hand grenade last year.

Thebehali is undismayed by the hostility. He says he is doing a valid job and he works hard at it, coming to the office at 7 a.m.

"My job is not to run a political pressure group but to get on with the practical business of improving the quality of life for the people who live here," he says.

Thebehali is as scornful of Motlana as the latter is of him. "He and the radicals are very vocal and get all the publicity," he says, "but they don't achieve anything to help the people who are living here. How can you tell a man who has no house that he must wait until the day of liberation?"

Thebehali says he has $400 million worth of improvement projects going on in Soweto, aimed at electrifying the whole township by 1984 and eliminating a building backlog of 15,000 houses. He gets money out of the government for scholarships and pushes for improved school facilities and other services.

To Motlana and the radicals, that is simply oiling the chains of oppression. They say no self-respecting black should help make the government's system work. A solid front of noncollaboration, they say, would force the government to change the system.

The animosity between the two approaches is indicative of deepening rifts among blacks. Factionalism is rife and infighting intense. The first big divide is between what are called the "system blacks" and the noncollaborationists.

Even Chief Gatsha Buthelezi, the Zulu leader who is one of apartheid's most vigorous opponents, is reviled by the radicals as a "system black" because he has accepted an office in the tribal homeland system.

There is a rift within the "system blacks," too, between those who go all the way with the system, such as homeland leaders who accept the status that is termed independence, and others like Buthelezi who use the system against itself.

Buthelezi and his allies have obstructed the government's plans by refusing to accept independence for their homelands. He regards those who have taken independence as "sell-outs." They say they have freed their people by making them politically independent of apartheid South Africa.

The noncollaborationists are also divided, between those who believe in working with sympathetic whites and those who do not.

Advocates of black consciousness say the roots of oppression in South Africa are fundamentally racial and even the most sympathetic whites are therefore inherently "part of the problem." The more Marxist-oriented groups say the main dynamic in the South African conflict is class rather than race. They have longstanding links with left-wing whites and look upon the emerging black middle class as "part of the problem."