Hopefully someone there will give you a real answer, but checking the RR database it does not show a trunked system for any railroad in Nevada. So I would program them in conventional, FM.
I had thought that almsot all RR oppeerations were conventional.
If they have trunking it would have to be very local, like a yard, because the AAR likes to keep things standard, and Trunking prior to P25 would be single vendor.