Looking at all of the best photos I have to go by, I am pretty sure that the 'Coffee Can' is self contained VHF antenna with no other whip attachments to it.


Photo of possibly an early test of VHF Locotrol with the lead unit having two of these antennas, one for voice and one for Locotrol. The third unit, a DD35B, can be seen sporting the same dual-antenna array. Yes, Locotrol used VHF in its infancy, CPR used it with their 'robot' cars and older Sinclair Excaliber antennas.








Oddball Coffee Can antenna atop a wagon wheel ground plane


Looking above with only one antenna visible, it is highly doubtful that this locomotive is using UHF.





As for the dipole, I doubt that it is UHF as use for that is reserved for telemetry and I don't think this New Haven ALCO was using anything but VHF at the time.



Compare above to the other view I have from the top of the UP car.




All of the above photos with the exception of the ATSF caboose and the last one were retrieved off the usenet (newsgroup) alt.binaries.pictures.rail. No infringement intended.