The Cold War goes nuclear in the mid-'60s. Yugoslavia is a neutral, and doesn't take more than maybe a few nukes; while the refugee crisis is very dangerous in the immediate aftermath of the war, the country pulls through, and eventually emerges as a local powerhouse, due to retaining significant amounts of prewar infrastructure. This wealth, along with the shared experience of surviving the Third World War and its aftermath, helps the People's Republic of Yugoslavia survive beyond Tito's death [which might come earlier than OTL on account of increased radioactivity], avoiding the fracturing that occurred in the 1990s.
Admittedly, I doubt this Yugoslavia would be reaching the wealth of the OTL Benelux for a while yet, but it certainly would be richer than TTL's Benelux. And while Yugoslavia would probably be more likely to fracture under the stress of the Third World War beyond its borders, I could see it holding together. Admittedly, I'm not sure that the country would escape warfare, but if it did, it might have a shot.
Admittedly, I doubt this Yugoslavia would be reaching the wealth of the OTL Benelux for a while yet, but it certainly would be richer than TTL's Benelux. And while Yugoslavia would probably be more likely to fracture under the stress of the Third World War beyond its borders, I could see it holding together. Admittedly, I'm not sure that the country would escape warfare, but if it did, it might have a shot.