Just my personal opinion, but I think the RS-3 is one of the nicest Diesel locomotives, in terms of aesthetics, from the 60's and 70's.
I rode behind them lots of times on the LIRR, between Jamaica and Speonk and other stations.
When Weaver (?) issued them, I bought a couple and had them custom-painted for the LIRR by a very talented guy in a hobby shop in Babylon. He also did a few Wms "Madison" coaches and painted them in LIRR livery. I'll dig out a few and post some pictures.