Exact Dates of Emblems

[NW Modeling List]

Hey Everyone!

Your help is greatly needed! I am modeling the N&W Pocahontas 
division in HO for my model railroad. I want to model the transition 
era (such a great time to model with the peak of N&W Steam 
technology) but I need to know a basic fact that I am having trouble 
finding. I am pretty sure the N&W Switched to the Blue and Yellow 
paint scheme after the merger in 1965. However, I was wondering was 
it at this time that they switched from the script style circle 
emblem seen on the N&W HS emblem to the more simplified circle with 
the half circle areas filled in? I need to know so I can have the 
correct paint schemed early diesels doing the dirty work next to the 
steam engines. Thank you so much if you can help me out!!!

Logan Greene