I was actually in Havana in the early ‘90s. What I saw there were not so many of the classic US cars from the ‘50s, but heaps and heaps of Trabants and other Eastern Block trash-cars.
These days, there are around 60,000 classic American cars in Cuba. Experts estimate that about half of these cars hail from the 1950s, while 25 percent are from the 1940s and another 25 percent are from the 1930s.