I found some images of my model before it was destroyed. The whole locomotive was redesigned and enhanced. All details are now 100% prototypical.
Here is a brief history of the GP15-1.
The GP15 was only produced as a trade-in item. It entered prodution in June, of 1976 by EMD. The GP15s used the old diesel's Blomburg D trucks, main generators and traction motors which the railroads sent to EMD. EMD sold around 1000 of these units. The main reason for the trade ins were because of the lack of short-line and switching engines in the 70's. The GP15 had a rather low horsepower, (1500) and featured a smaller fuel tank than what EMD currently had out that time. The main external feature which can show a GP15 is the air intake vents are in the back of long hood, which is also on the SD40T-2, and SD45T-2, which its sometimes mistaken for. The road which owned the most GP15s is the Missouri Pacific. Today many Class 1 lines have sold their ones to short lines and leasing companies. Union Pacific still uses GP15s for yard work and light road duty still after 31 years of work.