UPDATE:
Upon inspecting the cleaned and dry housings, I can see remnants of the plating on the exterior lip, and some of it on the main body of the housing. Most of it is on the bottom where it would have been more protected. There is especially a good amount on the surfaces of the mounting tabs that were against the sheetmetal openings)
I tried to take pictures, but no matter how I tried to change the lighting and camera settings, it was hard to tell where the plating remnants were.
I'm beginning to think the whole housing had this dull chrome plating, inside and out.
Can anybody look at their housings and tell what you find?