Scratchbuilding an HO EMD FL9 Diesel-Electric/Electric loco from an Atlas HO FP7 is described in issue 3, volume 15 (Sept. 7, 1984) of the New Haven Shoreliner magazine. The FL9 is about 4 feet longer than the FP7, has different trucks (Flexicoil B in the front and a Flexicoil A1A (a C with the middle axle de-motored) in the rear) and has some miscellaneous chassis and body modifcations — differences in porthole and vent locations, different horn, different dynamic brake fan, and different steam generator details (or HEP generator-set details if you are modeling a current (rebuilt) FL9). The bulk of these modifications are covered in the Shoreliner article, but I did some things differently — these diffrences are described in the document referenced below.
fl9notes.zip Zip Archive containing the scratchbuilding notes as a PDF file. Also included are PDF drawings of the third rail pickup assemblies.
Here are some pictures I took of a "typical" AMTRAK FL9 (AMTRAK #486, sitting at the Albany-Rensselaer, NY station). I found these pictures very helpfull in getting some of the details right.
Front of AMTRAK 486 (FL9)
Rear of AMTRAK 486 (FL9)
The pictures below are blowups of the two trucks. I found these very usefull in figuring the dimensions, etc. of the third rail gear.
Front truck of AMTRAK 486 (FL9)
Rear truck of AMTRAK 486 (FL9)
Photos of the completed model (#486):
View of my HO FL9 on the end of a bridge
View of my HO FL9 on a test track
CLoseup view of my HO FL9
Another view of my HO FL9
Notes on finishing.