While some multi _manway_ single compartment tank cars have been built since 1960, for phosphorus for instance, I can't recall ever seeing a multi _dome_ single compartment tank car.  Can't say that such did not exist, but if such did exist I'd love to see a photo.  

This is not to say that all the compartments of a multi-compartment tank could not be used for the same product.  Probably happened a lot during the war years.

Yes, dome-less non-pressure tanks (spec ICC-111) were built before 1960, first by Union Tank in 1956 IIRC, they were not by any means common until after 1960.

Scott Chatfield