PC: Roof color

["Rob Carlo" <robcarlo@xxxxxxxxxxxxxxxx>]

PC fans,
    Here's another painting question to debate about.    I model a lot of
passenger equipment and have always been puzzled by the roofs of PC
passenger cars.  I know the green smooth sided and ex NH cars had black
roofs but cannot figure out what the policy was in reference to ex NYC and
ex PRR stainless steel cars.  I've seen photos of Budd and Pullman Standard
cars with both painted (black) and unpainted (silver) roofs and have read
that the official scheme was black roofs,  which doesn't explain the
unpainted roofs.  
    Anyone know the answer?
Thanks!
Rob