RDC question

Can anyone tell me what purpose the stainless steel boxes mounted on the end doors of RDG's RDC's served? From photos I've seen they appear to be open at the top, as if they were for paperwork or torpedoes & flags, but I can't imagine why they would be mounted on the outside if that's the case.

The Budd electric MU's had them as well, although not as pronounced. Since the doors covered the engineer's controls when they were open for MU operation, they may have been contoured to better fit around the control stand.

http://www.thebluecomet.com/rdgMelrose1.jpg

At least some of the PRSL RDC's also sported this feature.

http://www.thebluecomet.com/prslRDCabsecn2.jpg