Penn Central Radio question

Does anyone know what kind of VHF radios were delivered on the following Penn Central units:

GP38
GP38-2
GP40
SD40

A buddy and I who is also a radio-phile were listening to a recording I made in the early 90's of Conrail radio traffic. Many of the units listed above were still in service then. When an employee would transmit from them, we noted that they sounded like they had a built in mic on the control head (backround cab noise very audible), and that they sounded like a re-transmission or patched signal of someone talking in a tin can, or a tunnel.

Someone told me one they thought it was Wabco or RCA.

Pretty obscure question, I know, but I would like find out what kind was used to see if I could acquire one (working or non) for my collection.

Thanks, Adam

The older units that did not have "clean cab" radios probably still had the standard AAR 4 or 8 channel control head with the built in mic. The radio could have been any compatible AAR mounting radio: MICOR, MOTRAN or WABCO.

The "tin can" audio was typical and, on some units with 24 brake equipment, the control head was right next to the brake stand. The noise of air blowing during a brake application would just about wipe out the voice.