Stephen, that is an S-1 it is the non turbo version of the 539. the Blunt trucks are on the S-1 and S-2 while the S-3 (non turbo 539) and S-4 have AAR trucks. The S-1 and S-3 are shorter and have some differences in the doors compared to the S-2/S-4
Charlie
A pair of NS loco's still in Conrail Blue head up CA-51 at Winslow, NJ December 14, 2011. This was the last date I was able to get photos of them together before they left South Jersey to be repainted in NS colors.
Shore Fast Line U30B at Pleasantville, NJ December 1991. 2876 had just returned from a run to Dee Lumber in Linwood. This section of rail line is now a bike and walking path.