Good luck
The only saturation I see is re-hashing of E8's, F3's, F7's, PA's, GG1's.
The K-Lionel SD75 was their Best model to date. Too bad they were ashamed of it. The only updating it needed was a scale fuel tank.
You will have more of a chance convincing a Railroad to Paint one in a Heritage scheme and then it will probably be made.
Can a guy get an SD45-2, F45, GP40X, GP50 or a B36-7 for a change???