Colors of the INTERIOR of HW Cars Vestibules

I am working on a set of HW car models, and I am interested in finding out what color the interior of the vestibules--walls, floors, and ceilings--were painted.
Thanks for any info.

 

The vestibules were Pullman Green, but the floor and steps were black.

Ken McElreath

 

Thanks! I would have assumed that the interiors would have been a lighter color. Glad to learn better.