EMD's SD-40-2

Technically, it's not. The Alco "RS" series were the Road Switchers, which were switcher locomotives with trucks that would allow for operation on main lines. The EMD equivalent was the GP7, with the "GP" standing for General Purpose. "SD" stands for Special Duty, although you'll find that some railroads actually use these thirty something year-old diesels do their switching work today.
I don't have my book right in front of me, but I seem to remember around the 70's they started making SD40's, as for the "-2" versions, not sure.
Thanks Kennedy, I was close, I knew they had been around alot longer then one thinks.