Form this set of pictures, I see these models have great detail and with excellent weathering. Some of your SP engines have a box on the cab roof. Air Conditioner/Heater? from the sight glass near the radiator I gather that these are SD-40-2's, SD-40-T2 "tunnel motors, and one SD-45-2. One question--everything I have read says that -2 models have the "shock absorber" on the center axel of the C trucks; some of yours have it some don't;
is this intentional?