Yep, it was something around 2000 million dollars. Last i heard Cuba wanted to pay it with medical attention for Argentinians, or something like that. But they are never going to pay it if you ask me.
Unfortunately, Argentina having committed the world's biggest debt default to the day, has no moral ground to condemn Cuba to much on this issue.
Oh, and the loan was given by president Hector Cámpora in 1973. Campora was a far left peronist president that served as a bridge to bring Peron back to the country. His presidency lasted only 3 months, but in that short time he managed to do things like this loan and granted amnesty for "political prisioners" (terrorist guerrillas) and even a couple of serial killers.
If it was in dollars then most likely there was no real value behind. Just tons of high quality paper. When was Argentina in such tremendous economical shape to lend money?
And under what kinda guarantees?
By the end of WWII Argentina had no foreign debt and was a loaner of some European countries, including the UK, most of the debt were from food exports. England for example, owed Argentina about 140 million pounds which were kept blocked in the UK. We didn't invent debt default you know.