Soviet Union lent only moral support to revolution waged by Greek communists and other anti-monarchists although Stalin feared Yugoslavia's material aid to the revolution might signal a Pan-Balkan movement independent of Soviet control...nominal and indirect Sovet involvement in Greece was only one instance of tactical retreat that resulted in 'sell out' of European working class even as its limited role was used by Truman to justify Cold War...
re: Yugoslavia's 'market socialism'....central planning was greatly weakened in early 1950s, agriculture remained private (though redistributed from pre-WW2 ownership), prices of most goods & services were marketized, economy was open to extensive trade with capitalist West, a good deal of small-scale private enterprise existed in service and tourist sectors, free emigration for citizens was permitted, profit-making governed success/failure in larger self-managed factories, worker participation through councils...
also...mass unemployment, chronic inflation tied to tendencies of Western capitalist economies, growing foreign debt related to need for importing Western goods and technologies (fostered by Carter's 'kinder/gentler' Cold War), divergent levels of development among the six republics and two autonomous regions comprising the federation...Michael Hoover