The same two cars were done by Roco in N Scale. (IIRC the HO cars were also done by Roco, origiinally for AHM).
The lower height framework car in the N Scale version had cylindrical containers with coned tops as a load.
The higher height framework car was a LCL Container Car. MiniTrix imported this car without any load.
I've not tried to document the prototypes for these cars but seem to remember seeing photos of both at one time or another, maybe in a CBC.
Pictures of the loaded N Scale Calcuium Carbide Car in N can be found at http://Irwinsjournal.com/a1g/a1g_3021.jpg
These cars were part of a series using a common underframe that also included a Pulpwood Car in both HO and N.
Charlie Vlk