Santa Fe "book end" paint vs yellow war bonnet scheme

Model Railroader Prototype information for the modeler
1

I have a book of Santa Fe paint schemes but am unable to locate it at the moment. When did Santa Fe begin using the Yellow bonnet scheme on GP and SD units?

2

1972

3

And specifically April 1972. The first unit painted in the yellow warbonnet was the SD45 #5524 followed by the U28CG #7904 in June 1972.