EMD GP35

I see references online that Athearn has produced that road number, so it's probably theirs. 

Athearn GP 35

“ Blue box” model. Looks like it’s had a rough life.  Undecorated parts may still be available.

Agreed.  Looks like a blue

Agreed.  Looks like a blue box Athearn GP35 with the non-scale width hood.

Athearn GP-35

You have an Athearn GP-35, not for sure about vintage dates. Earlier versions have cast metal sideframes on the trucks, later versions have better detailed plastic sideframes. Earlier versions have a dark grey motor that is as wide as the inside of the body shell, later versions have a narrower bright metal motor. Parts are fairly easy to come by and older versions can be upgraded with newer parts.

My example dates from about 1977 and has been upgraded with a few detail parts, Kadee couplers, painted handrails, new number decals and Northwest Shortline wheelsets. Yes, the body is a bit over scale wide and the details are not super fine, but this cherished model from my childhood still runs very well.

Cannon and Company used to make a cab kit that was designed for the Athearn wide bodied models should you not be able to find a new cab roof.

Cab Roof

From Athearn Blue-box SD-45 of the same era should also fit nicely.

Espee over Donner