Stalin dies in 1944, and his successors have less interest in screwing around with postwar borders so that they only detach the northeastern part of the Reich, leaving the finger that extends south and east with Germany.
East Germany thus has a little more coal and a little more steel, but given such serious ongoing issues with the basic nature of the centrally planned economy it's doubtful they could match West German economic performance unless they had Tito-like leaders willing to sacrifice some orthodoxy for economic plasticity.
The Yugoslav system of self-management was, in principle, operable with a "hands-off" from government if introduced slowly and with sufficient care. In Yugoslavia itself, self-management was seriously considered and implemented, but continuing interefernce from the government prevented it from being as successful as the hagiographic post-Tito/post-1990s writings online would have us believe.
Bottom line - with extra coal and steel East Germany makes less junky Trabants, but absent other major butterflies contends with the dual inefficiencies of a highly entrenched security apparatus - the Stasi - and a centrally planned economy.