Even though there a railroad fonts around, the railroads would often change. In particular the "good olde days" the lettering would vary from order to order or even from shop to shop. There wasn't any big, huge printing presses printing big huge vinyl decals. It was all done by sign painters at each location, and different sign painters even at the same locations. While there may have been stencil for the smaller stuff the bigger lettering and logos were often made by laying out the design on paper and then punching many small holes by using a pounce wheel (them things used by modelers to make rows of rivets in a hurry). Then the paper would be taped to the car side and powder puffs were used to put the design on the car with powder. Remove teh paper and teh sign painter would use the powered dots as a guide for the actual paint. Lots of room for variations here. Plus, each run of cars would have new artwork drawn as the chances of one layout being identical to the next project were practically nil.