Your link doesn’t seem to work for me. Takes me to the Trains.com Forum Page.
I know Athearn did have a problem with it’s Blue Box SD45. For what I know it was 2 or 3 scale feet wider than the real SD45. I’m not sure if that helps as it not the same locomotive!
The older Athearn hood units were about a scale foot too wide. I run them with some of the scale width Athearn units and it isn’t all that noticable.
As stated the Athearn GP9 is actually a GP7. I make a kind of faux GP9 by removing the two louvres under the cab and the louvre on each side of the hood that is just past the dynamic brake blisters.
Having been out of HO-Scale for more than a quarter of a century I don’t know whether Uncle Irv and Company ever retooled the body shells for their GP7/GP9 but if they didn’t then this is most likely one with a 7 foot wide HOOD instead of a prototypical 6 foot wide HOOD.
I disagree with forum member Mr. SP; when these are coupled with a scale-width unit and viewed from above this oversize hood-width becomes readily noticable. In the mid-'70s when Atlas made their first HO-Scale offerings with their scale-width hoods I saw one of these “dummies” mated up with an Atlas unit and it was one of the first things - indeed probably the first thing - which I noticed.
The SD9 looked good enough that it was easy to look past the width. The problems with the GE and GP35 and SD45 models was that the front windows were a total mess, not even close to looking good, mostly on the EMDs. Also, and not to get too picky because I still liked the model, the SD45 had too many engine access doors and too few radiator grills.