A question for Dutch

[fl9m2026]

Dutch, recognizing your broad field of knowledge on RDC's, I wonder if you can answer a question for me:

I've been going over all my photos from the net and other sources to help me detail an O scale Sunset Models brass RDC I recently purchased. The model represents NYC M-450, the first production Budd car sold to U.S. railroads.

In looking at the material I have, I made a discovery about NYC Beeliners that I could not find on any other railroads Budd car;

On each truck, there is a large, outside hung appendage or mechanical device at the top/rear of the truck frame. It's design/purpose is unfamiliar to me. They appear to have been added later in their careers as they were not present in any delivery or other early service pics I've seen of Beeliners. You can see what I'm talking about in these pics;

http://rr-fallenflags.org/nyc/nyc-M455jra.jpg
http://rr-fallenflags.org/nyc/nyc-M499wka.jpg
http://rr-fallenflags.org/mncr/mncr-rdc56as.jpg In this pic, the device is only on the truck on the opposite end
http://rr-fallenflags.org/mncr/mncr-rdc56ags.jpg
http://www.morscher.com/rr/1977/19770616_12.jpg

Any help is appreciated.

[DutchRailnut]

NYC relocated the sand boxes to trucks, the original car body boxes would get plugged up with sand( due to water leakage into boxes) and could only be freed up at a platform or by banging on the RDC skin.
this left huge marks , so they made truck mounted sand boxes with associated piping.

the original box is little sliding hatches in skin of RDC just below windows.

[fl9m2026]

Many thanks Dutch! I knew if anyone could solve the mystery, it would be you.