This is odd on RSRR(GWI)????

Today i saw pasted railroad covered hopper cars on Rochester Southern railroad. This is what i saw: alot of GNWR,GATX,CN,SP,BO,CO,NP,NW and CR. It was heading southbound to the salt mined. It was not interchanging with LAL or CSX. So my question is does GWI use former railroad covered hopper cars???