One of the great things (among so many others) about MicroTrains is that they will consider doing cars that you want if you have the info about them. I model the NWP during the 50's and supplied the data and photos for one of the overnight cars they did as well as the Hercules 'reefer' and tank car. So while they haven't been doing much (lately) that I'm excited about, I could always provide the info and try to convince them to do something I do want.
Hey MT, are you interested in a NWP billboard wood caboose with orange ends? LMK as I have the info ready to go.