Is there a “directory” giving the ownership markings on freight cars? e.g. CSX.
Here are just a few of the sites that have some informanation.
http://www.nrhs.com/reporting_marks/
http://www.nrhs.com/reporting_marks/company_reporting_marks.htm
Not sure of your location - but the Canadian Trackside guide has a listing of most if not all of the markings eg , SULX - together with the owner names etc
Was at trackside this afternoon on CN - thought struck me a I watched the cars go by - have you tried the UMLER website - that may give you some more information .