FWIW, I just now noticed that the "brush plate" on this unit is the same odd "dijon mustard" color as is on my (for sure) 1946 #310, so I guess that makes sense...(?) My other 300 has a black plate, which matches my other locos (300AC, 312, etc.)
I find this kind of "detective work" on these models fascinating...
Mark in Oregon
PS: I have a couple of "Midgage" cars coming in the mail, so be prepared to field questions about those too.