For example, all SD40-2R's retain their SD40 long hood and frame. The hood lacks a sight glass and pilot anticlimbers, both of which are present on the SD40-2. But the similarities among units end here. For some unique spotting features of individual units, check the 'notes' section of the photos above. But here are a few features that I have noticed.
Some units have ratchet brake levers in the nose, while others have brake wheels.
Painting details vary also among units. Conrail's SD40-2R's are an interesting locomotive to spot. Two of Conrail's SD40-2R's had a brush with fame in their previous SD40 lives. Most information came from Conrail Locomotive Data books and my own personal experiences with these units and SD45's. Robert S. Waller .