The overall scenario I used for mine:
First point I think bears asking is how big the country's economy and population are, and whether a considerable drawdown of the forces would result, and what brought it all together.
My scenario starts with a National Party win in 1948 and South African units fighting with distinction in Korea. The NP decides there is nothing to gain by antagonizing Britain and so the loud rhetoric doesn't come to pass as much, and the NP decides its better to allow more white immigration than OTL, thus somewhat swelling the white population. A prospering economy in the 1950s and 1960s means that the NP has little difficulty keeping power, though by the 1960s the work of groups like the ANC is starting to make an impact on the monolith of apartheid. The ANC does not respond to the Sharpeville massacre with violence (at first) and stays a legal organization in the early 1960s. Mandela joins Tambo, Mbeki, Slovo and the others in Zambia in 1965 and as such his imprisonment becomes much less of a cause celebre for the anti-apartheid forces. The 1960 Census reports whites as 23.2% of the population (OTL was 19.3%) in the Republic of South Africa.
South West Africa is formally annexed by South Africa upon the formation of the Republic of South Africa in 1961. South Africa's sky-high birth rate is felled rapidly by prosperity in the 1960s, which slows the nation's population growth during that time. Hendrik Verwoerd's plan of "Grand Apartheid", the separate homelands for various black tribes, is felled by loud opposition from portions of the National Party in 1960, and the following year Verwoerd focuses South Africa's considerable resources on the development of the non-white racial groups, with the goal of them giving up political power in return for prosperity. This social contract has almost-immediate results, with a surge in school registrations and other work in the 1960s and early 1970s and a massive drop in unemployment among all races during that time, with the NP's plans focusing on building infrastructure and advance the national will. This also results in the creation of thousands of small and mid-sized companies owned by blacks, Indians and Coloreds. The Homelands idea never fully dies, but it never again gains the support of the majority of South Africa's government, helped along by the opinion among many whites that one day apartheid would be untenable.
By 1970, South Africa's unemployment rate for whites is below 2%, below 7% for Indians and Coloreds and less than 10% for black South Africans. Laws needed to allow this "African business class" to grow are passed during this time. The 1973 oil crisis hits South Africa hard and causes the first real economic slowdown in the nation since before WWII. This also leads to the National Party losing a majority in South Africa's parliament in elections in 1974. South Africa's opposition makes the case that with nearly all of South Africa's neighbors engaged in civil unrest on a huge scale (Rhodesia, Angola, Mozambique) that if civil rights were not improved for all South Africans it would inevitably lead to confrontations between whites and everyone else, and that while the business classes of other races were capable of working in South Africa, they wanted more rights under apartheid. The fall of the Portuguese colonies in 1975 drives the point home further - but when massive guerilla activity breaks out in the border areas between Angola and South Africa, the SADF responds by attacking guerrilla positions inside Angola....which draws a response from Cuba, which deploys units to both the Marxist former Portuguese colonies.
With apartheid being slowly pulled apart, the arms embargo never happens, and the Cubans and South Africans meet for the first time in March 1977 one hundred and eighty miles north of the border inside Angola. It's not a pleasant fight - the SADF, despite a considerable amount of newer equipment, fights to a draw against the Cubans. The 1977-1978 battles in Angola force the SADF to massively increase its strength to match the Cubans. The SAAF's helicopter forces and the SADF's elite forces spend most of the late 1970s assisting the Rhodesians, but Rhodesia eventually does an internal settlement deal in 1980.
The 1980s sees the armed forces of the Communists build up in a big way, forcing the SADF to do so as well. Within the context of the Cold War, South Africa quickly does become NATO's southern front, as African resistance groups and governments battle it out with Cuba on one side and South Africa on the other, while the latter works to sort out its social problems. But the clincher of the need to change comes in 1980, when a raid on a Pan-Africanist Congress camp in Maputo, Mozambique, by the SADF's 44 Para results in a Cuban division being based there, and forcing a South African armored brigade to be based at Nelspruit. On May 27, 1980, the a SADF patrol just off the N4 is fired upon by two Cuban Air Force Mi-24D helicopters, killing three Ratel armored personnel carriers and two Land Rovers and taking the lives of 17 SADF soldiers. Two days later, SADF Mirage F1AZ attack aircraft, Buccaneer S.50 strike aircraft and Canberra B(I)12 bombers flatten the Cuban base at Maputo's International Airport. South Africa's 81st Armored Brigade and a Cuban Armored Brigade soon are encamped on either side of the border post at Komatipoort, a situation that several times in 1980 and 1981 erupts into skirmishes. Both sides eventually withdraw back to Nelspruit and Maputo in mid-1981, but the situation reinforces the need to fight back against Communism and to come to an equitable agreement in South Africa to make sure what had come to pass in other nations does not happen if apartheid falls.
The 1980-81 battles catch the SADF in the middle of a massive modernization plan, which had begun in 1974-75 as a measure to improve the economy of the country after the energy crisis and had created a variety of improvements to South Africa's defensive forces. After the 1980-81 fights, the government in Pretoria gets more help from abroad, but this comes with the condition that they sort out a government that includes all South Africans. To this end, the ANC is legalized in September 1981, and a jubilant set of ANC leaders returns to South Africa in November 1981. 1982 and 1983 in Pretoria are occupied with plans for a new constitution, but in the meantime economic prosperity continues in the nation and the buildup of the SADF's capabilities continues unabated. By now, white South Africans, who make up 24.2% of the population of the country in the country's 1981 census, are willing to work with the other ethnic groups to ensure the nation's security. Mandela and his side of the debate soon work out a new constitution, which goes to a referendum to the nation on September 8, 1983.
The new constitution sets out a single lower house elected by majority rule, with an upper house with an equal number of representatives for each population group and divided by constituencies, thus forcing any member who seeks to run for that upper house to reach across racial and ethnic lines. All political parties are allowed to run except for those advocating racial superiority or violence and the cabinet and government positions are not allowed to be filled entirely by one group. South Africa has one State President and two Vice-Presidents, as well as a speaker of the Lower House - and by law, these are to be filled by members of the four different ethnic groups. An embedded set of rights of the individual and rights of the state make the nation look more like a federal republic, which was a key demand of the National Party government. Presidents are limited to one term in office, but Prime Ministers are allowed two terms.
The referendum is open to all South Africans, and easily passes with wide support across all racial groups, though black support is lower than other groups. Enacted into law on October 1, 1983, the new constitution for South Africa is followed by an election for South Africa's new government, set for March 15, 1984. It is held with the only problems caused by one white terrorist attempt which ends badly and three minor attacks by communist guerillas. The ANC wins handily with 56% of the vote for the lower house, but the National Party surprises both with its vote count coming in at 30% support, winning both the white and colored racial groups. Nelson Mandela is sworn in as South Africa's first black President on March 25, 1984, at the Union Buildings in Pretoria. The whole process is a force which is inspiring to both South Africans and foreign investors, and South Africa's 1980s economic growth rises from a sluggish 2.3% in 1980 to a stunning 9.7% peak in 1988, and per capita income in South Africa rises across all races by over 70% between 1980 and 1990, with black South Africans benefitting the most. Mandela's many promises in the 1984 campaign are energetically set to by South Africans of all races, and such is the level of success that an interview by Verwoerd in 1988 to the Rand Daily Mail has him state that "South Africa is advancing further than I thought it would in my lifetime, and our people, all of them, should be proud of what they have accomplished. If I had known this is what would be the result of a move towards majority rule, I make no statement in saying that I would have spoken to Mandela in the sixties." Mandela retires after one term as President in 1989, giving way to Steven Biko's term as President of South Africa.
Meanwhile, the SADF buys billions in new hardware between 1975 and 1990, with the goal of advancing its goals to be a modern fighting force, and after the 1980-81 skirmishes black soldiers are soon coming into the SADF in numbers, numbers that grow dramatically following the 1983 constitution. With high minerals prices providing a cushion of money for South Africa in the 1980s, the SADF's capabilities grow massively during this time period. The United States scores big sales to South Africa's defense forces in the forms of selling the F/A-18 Hornet fighter to the SAAF in 1982, while the SA Navy buys four mostly-completed air-warfare destroyers from the United States in 1980 - the ships had been intended for Iran but the order had been called off as a result of the Islamic Revolution. Despite the American successes, much of the SADF's equipments are filled by domestic sources and most of the others are won by the Europeans. A huge score happens in reverse of this in 1984, when Armscor's G5 howitzer is selected by the Spanish Army to replace many of the varied artillery guns owned by the Spanish Army. The G5, which is developed in large part due to the work of Canadian engineer Gerald Bull, is sold to quite a number of countries as a counter to the long-ranged Soviet M-46 130mm howitzer. Likewise, Saudi Arabia orders a number of Ratel APCs in 1985, but a potentially-huge order from the Saudis ends up going to the rival American M113. South Africa and Israel's long history of co-operation is added when the two nations co-operate on the development of a "revolutionary tank", which becomes the Merkava III. The Merkava III enters SADF service in 1987.
By 1990, the SADF is the highly-potent fighting arm of what is unquestionably Africa's strongest nation, though economic development in Zimbabwe Rhodesia and Botswana had done wonders for those nations. As the communists retrench themselves in Europe, Cuba is eventually forced to withdraw from Angola and Mozambique in 1990 following the Brazzaville Accords, which also sees the SADF agree to not get involved in the internal affairs of either Angola or Mozambique again. 1990 sees the first African car maker emerge from SA and 1991 sees the country's GDP per capita pass $12,000 per person, with a vibrant and strong private sector in dozens of industries helping both the country's economic performance and its unemployment levels. The 1991 Census sees the population at 31,122,450, with that population being 57.6% black, 23.8% white, 12.1% colored or mixed-race and 5.2% Indian.
