GP9B Conversion "Cab"

"Cab" for converting an [Athearn "GP9"](https://hoseeker.net/assemblyexplosionAthearn/athearndiagramgp9flywheeldrive1973.jpg) into a GP9B [B-unit](https://en.wikipedia.org/wiki/B-unit). Note that this thing is unlikely to work on locomotives with a scale width hood. Though sold as a GP9, my understanding is that this shell actually more closely resembles a GP7.

Equivalents of this thing are available commercially. Though haven't yet, am planning to smooth the print with filler putty prior to printing.

As in the prototype, the roof of this thing is not aligned with that of the front or rear hoods.