If you saw empty flats in Northport (Duke) they could of been from Ozone Lumber which receives cars at Richmond Hill team track. The RS 30 used to serve that costumer right out the gait on the Lower Montauk. That and American Tissue where the only Eastbound moves on a Port Jeff Branch run. Than they would run around at Northport service everything westbound. This may have included Kleet, Nassau-Suffolk, Huntington Team, and Gallo Wines. Sometimes the slots were really tight and you had to really move to get out of LIRR's way. One guy would put the Kleet's in Nassau Suffolk and vice versa, and once somehow a Gallo wine boxcar in Kleet lumber!