JOHANNESBURG (Reuters) - South African stocks ended at record highs on Friday and looked set to keep their bullish tone next week if metal prices hold up and the local currency keeps weakening. The rand had been strengthening for much of this year but has been on the back foot since June due to the threat of more strikes in an economy already reeling after a five-month stoppage in the key platinum sector. Spot platinum prices rose above $1,500 this week for the first time in 11 months, and gold is also holding on to gains made in June. "The thing to keep an eye on is the rand/dollar exchange rate and also the commodity prices - gold, platinum and iron ore," said Greg Davies, an equities trader at Cratos Capital. "That is probably where the next leg up of the bull market will come from, the resource and mining stocks." A weak rand often tends to support resource companies which earn in hard currency but pay salaries and suppliers in local tender. Both Top-40 and the All-share indices traded 0.3 percent higher, their highest close ever, ending at 47,080 and 52,060 respectively. The gold mining index was up 0.7 percent with Harmony Gold gaining the most with 1.5 percent. Unremitting labour strife in South Africa forced General Motors to suspend production at its main plant in the country after a strike hit parts supplies, it said on Friday. Violence erupted on some picket lines as the wage strike by the National Union of Metalworkers dealt another blow to an economy damaged by a five-month walkout in the platinum industry that only ended last week. [ID:nL6N0PF2E2] With Wall Street closed later for Independence Day celebrations, markets were quieter than usual. On the Johannesburg bourse 131 million shares changed hands, lower than the moving average of 173 million in the last 14 days.