The first one out of the factory is the B23-7. Just like the U23B the only way to tell it apart is by the loco having 6 engine compartment doors vs. 8. You can also see the effects of the repositioned oil cooler on the long hood, as the wider part of the body, has moved fordward, to the engine compartment doors. SBD also placed a 10 unit order for the BQ23-7, this unit featured a "wide cab" that could house 5 crew members, for new cabooseless opperation. After the CSX merger, they were soon converted to B unit status, and had there windows plated over. Bellow is a U23B, followed by a B23-7, and a BQ23-7, so you can see the diffrence.
Collection of James Jackson
Next in the line of releases, is the B30-7. The B30-7 is only told apart by the fact that it has 8 doors for the engine compartment, vs. 6 doors. In this series, you also had diffrent classes of a B30. Also included in this class is the B30-7A (witch was only owned by MP/UP, and still is unless some have been sold to shortlines). It has a 12 cylinder prime mover vs. 16, for better fuel consumption, while still retaining the 8 doors, on the side, making them indistuingishable from normal B23-7's. Next in the evolution of the B30, is the B30-7A1. The Southern (now NS) is the only railroad to order this model. In this loco, the equipment blower has been moved behind the cab, from where it was in front of the radiator. You can see this by the large grilled opening behind the cab. Then we have the B30-7A(B) (the cabless verson of the B30), and the B30-7A1(B) (cabless verson of the B30-7A1). Note that on the B30-7A1(B), you can see the relocated grill opening for the blower housing, and above that a new box (location) for the dynamic brakes. a forrunner of things to come. Found below is a B30-7, then B30-7A1, followed by a B30-7A(B), and B30-7A1(B).
Collection of Kenith Belk
Next in the series is the B36-7, once again as with the U30B, and U36B, the B30-7, and B36-7. Here is a B36-7.
The next step in development came with the B39-8. There is manny spotting features, to set this apart from the rest. First off is notice how squared off everything is, no more roundness to the nose. Next you can see behind the cab the steped up long hood (now where the dynamic brake is), on the other end of the long hood, you can see that the intake openings beneath the radiator, are now angled down, and the smaller ones below, are standerdised, to one size, and approxmate location, in line. ATSF ordered the first units, of this class, but the changes at the time did not include any of the stuff at the rear of the long hood. Railroads that bought the B39-8, were the ATSF, SP, and GE lease fleet LMX (altough with the split up of the LMX fleet there are others now, ie. P&W, BC Rail (now CN), RLCX, MMA, CSOR and others). Below is a ATSF B39-8, and LMX unit, notice the diffrence.
The final GE 4 axles built to date is the B40-8. After producing just 140 units GE announced that it would be upgraiding the HP to 4000, and out came the B40-8. Spotting wise there is no diffrence in the B39-8, and B40-8. Latter on the ATSF specified a wide body on the B40-8, and thus the B40-8W was born. Here is a B40-8, and B40-8W. On a intresting side note one of the opperators, of the units NYSW, orrigonal had 25, all even numbered 4000-4048 (NYSW assinged units capable of MU even numbers, those that were not odd) units (a add on to a CR order, thats why they have the marker lights) assinged to it, when it was awarded the contract to temporally opperate the D&H. When CP finally bought the D&H the NYSW, returned all but 5 of the units, to the lessor, and the rest NYSW 4010-4048, became CSXT 5930-5949.
Next up we will look at 4 axle Alcos.