SD40-2

[NW Modeling List]

Gentlemen,
I have recently been given an SD40-2 N&W engine (the dummy one), but would like to know when this engine was used. 
My son and I are basically freelancing the Shennadoah Valley area in the mid-40's to the mid-50's and was wondering if this would fit that time period. (I know it's our road and we can do as we like, but don't want to get to far from that time).
I was also give a shell for a N&W diesel switcher, but have no idea what one. It has two (2) stacks and a sloped rear to the cab. It measures 6 inches long.
If anyone can help it will be very much appreciated.
I can be reached at rmacdona at bellsouth.net
Yours aye,
Macdonald,RB (Better known as Mac)