Pennsy LGB tank car

[morseman]

at a local model train show in town a few weeks ago, there was a LGB display & they had a black tank car with PENNSYLVANIA in large letters across the whole lenth of the car. It would appear it would have been a prototype of a 60 feet car and the lettering would have been two feet or more high. Can anyone shen any light on this if any such car existed and what it would have carried. I presume it would have been a MOW car? ???????????