Adding on with the above, all the RS2s and RS3s (aside from 1500) were bought for passenger service. Unfortunately for them (and the GP7s) they were replaced very quickly in commuter service by the RDCs, after only 2-5 years hauling passengers. After that they were used in secondary freight traffic.
Here is a RS-3 built in 1955, now in freight service in 1972, but it still has the steam generator, or at least its exhaust and square thingy (intake?).
http://www.rrpicturearchives.net/showPicture.aspx?id=2657932