If you ripped up a P42, it would look similar.
The only thing the cooling systems of a P42DC and a B23-7 have in common is: they have set of radiators, and there is a single rad fan. Other than that, the manner in which the fan and radiators is configured in the carbody and the cooling system strategy is completely different.
The cooling system on the P40/P42DC is unique and not like that of any other GE locomotive. The standard cooling system setup on all GE locomotives (to the best of my knowledge) U, D7, D8, D9, AC including the P32ACDM, consists of the following: a rad fan (or fans) driven by either a motor or shaft driven off the free end of the engine via the right angle drive; a set of radiators directly on top of the rad fan. Air is drawn in the vertical side screens or angled screens (if the locomotive has "wings"), through the fan which blows the air through the radiators, and is exhausted out the top of the locomotive. The system strategy is a wet/dry system, in which water is not always in the radiators. A flow valve or diverter valve which is regulated by water temperature, opens at the designated temperature allowing water to flow to the radiators for cooling. On the U-series and Dash 7's, the speed of the rad fan depends on the speed of the diesel engine. On everything else with a motor driven fan, there are three fan speeds, 1/4 speed, 1/2 speed and full speed. IIRC, full speed is 3000 RPM's. The speed of the rad fan motor is regulated by a panel with a series of thyristors and is powered by the alternator. All rad fans that are motor driven have the capability to be run in reverse to blow out the air intake screens (this is done during normal maintenance cycles).
The P40/P42DC cooling system has what as known as a wet system, whereas water is always in the radiators. If you looked at a cross section cut-away of a P42DC, you would see from bottom to top, the radiators, a set of shutters, and the rad fan sitting on the very top. During cooling, the rad fan must draw air through the vertical V-screens, through the radiators, through the open shutters, through the fan and exhausted out the top. My understanding for why this type of system was originally installed in the P40 was that the GE engineers, during the design stage complained that they could not install a standard wet/dry cooling system into the Genesis style carbody. The wet system was developed as a result. (Ironic that only 2 years later, the P32ACDM would be released with a standard wet/dry system, however to support a smaller engine, 12 cylinders versus 16.) The shutters are needed to retain heat when the engine is warming up or is very cold and opens when the fan turns on. The speed of the fan is driven by engine water temperature. One of the original problems with the P40's during the winter time (especially on trains like the Empire Builder) was that the radiator compartment was constantly getting filled up with snow coming in through the vertical V-screens. Shop personnel would literally have to shovel out the back of the locomotive before any work could be done in the rad cab. One of GE's modifications to the fleet was to add a second set of shutters, just inside the vertical V-screens (air intake). These shutters would open at the same time as the horizontal shutters on top of the radiators.
The only locomotives that I know of that had twin rad fans are the U25B, C39-8 and the AC6000. Everything else had a single fan. GE originally advertised the mechanical driven fan as better, as in not driven by a motor that could fail. The classic Dash 8's were the first locomotives to have motor driven fans. In my opinion, the motor driven fan is a far superior design.