You can have pretty much every country in the developing world go communist. The formula is going to be pretty much the same everywhere:
1) Strongman wins a power struggle.
2) Strongman tries to get support from the US but the US government opposes him, for whatever reason.
3) Strongman turns to the USSR (or in some cases China) for support.
4) Country becomes the "Democratic People's Republic" of whatever, puts a hammer and sickle in its flag, whatever.
This is not meant to imply that the actual Soviet bloc aligned leaders were not sincere leftists. But there are also plenty of examples of leftist intellectuals turned politicians who discovered the virtues of capitalism and "third way" politics and economics after entering the embrace of the USA.
Exceptions are places that are too big, powerful, and self-contained for the USA really to matter that much, the exceptions being China, which did go Communist, and India, which didn't but which has a large homegrown Communist Party (actually two). South Africa is another possible exception. Maybe Mexico, and that would be a really, really interesting ATL. But Argentina would stick to the formula.