I have a Burlington Northern 50ft. Car which looks like a box car but has 10 opening hatches on the roof,and4 under floor discharge shutes. It is car # BN 413328,capacity 192000. I bought it second hand but do not know just what it is called,or it;s manufacturer. It does not have the metal coupler box covers like Athearn.,but they are plastic moulded with the frame.The sides of the car have vertical steel ribs. It is green all over .
If if has no doors and the ends angle in a bit, it's a 100T covered hopper, I think. If it really is a box car - vertical ends and doors, it's a box car converted to grain/sand/cement/etc service.
Gene
I think the top car in this link is what you have.
http://www.cchobbies.com/hoscale/freightcars/walthersrrhoppers.htm
Rich
Ah, yes, it does sound like an Airslide Hopper...
It's a Walthers 50 foot Airslide. ;D