Retry Questions about Reading Co MRBX insulated boxcars

Fellow Reading fans,
I posted this a few years back and hope that some new information can surface. The original replys are attached.

Does anyone know what specific service these 40 foot cars were used in in the late fifties and early sixties? Anyone have pictures?

Some say :return when empty to Pt Richmond".

When were they returned to Merchants Dispatch.

Any contributions would be appreciated.

Probably the most mysterious cars that RDG operated. Word was that they were used for Campbell's Soup. Another story was that they were also used for Hershey's (don't know how true that one is). There were two distinct classes. The earllier ones had roof hatches and were smaller.
The newer ones had the Despatch Shops style end (looks like Pullman Standard type). Both types had plug doors. Earlier type had roman style lettering with blue heralds, while later style had extended gothic (NYC style) lettering with black heralds. There is a pretty good photo of one in
"Freight Cars in Color"-Reefers published a few years ago, and one on the rear cover of a Flags, Diamonds & Statues about the Reading. Gotta dig those out of my archives for specifics.

They were leased from MDT.
When first delivered from MDT, the first was painted white. Supposedly, E. Paul Gangewere saw it, and said "We don't have WHITE refrigerator cars" and ordered it sent back and repainted.

Looks like that was FD&S combined issues 17 & 18 Fall 1983. Great picture of earlier variety # 131. These have 6 foot plug doors, the later version had 8 foot plug doors. Wonder what they used the hatches for. These are bunkerless RB cars?? Cocoa beans for Hershey Chocolate like some of the old converted box cars?

Thanks for your interest.