Ahem. Tito, Kardelj, ... need I go on?
Amongst few high ranking Serbs was Rankovic, he got ousted from the party and denounced. Slobodan Penezic Krcun got killed under curious circumstances. Djilas was Montenegrin, he got denounced and ousted from the party in end of '50es and spend a lot of time in jail until he emigrated in 1966.
I will go as far to say that during Tito's life Serbs were never dominant in CPY central committee. It was exactly this that gave credibility to Milosevic and nationalists in Serbian Academy of Sciences in late '80es claims of anti-Serb politics and unfair treatment under Yugoslavia.
Only time when Serbs could be said to have "dominated" Yugoslav politics is short 1989. - 1991. period, where Milosevic and his ilk could count on votes from Montengero, and Slobo's newly appointed clowns representing Kosovo and Vojvodina. (im talking about votes in the silly "collective presidency" of Yugoslavia and central committee of CPY) Macedonia was never strongly pro Sebia and left Yugoslavia quietly in 1991.