I recollect Draper suggesting that class 'in itself'/'for itself' formulation is Hegelian residue in Marx, appearing in several works, last of which is discussion of French peasantry in _18th Brumaire_, and abandoned (properly in HD's view) thereafter. Readily apparent in the _The German Ideology_, clearest expression is in _The Poverty of Philosophy_:
'Economic conditions had in the first place transformed the mass of the people into workers. The domination of capital created the common situation and common interests of this class. Thus this mass is already a class in relation to capital, but not yet a class for itself." Michael Hoover (who, contra, Draper, sees class 'in itself'/'for itself' formulation in _Grundrisse_, the bridge between 'young' and 'mature' Marx)