Michael--I'd check with Microscale. They make exceptionally fine decals for just about everything, and you could probably get a sheet of SP diesel decals that would do just fine. Since you've got duplicates of the SD and GP's, you'd probably only need to change the last number on the locomotive, which should be fairly easy to do by just lightly painting over the last number, then applying the new Microscale decal.
Their decal sets are very accurate--I've been using the brand to number my Rio Grande steamers for years. Excellent quality.
Your LHS should have a good supply, or a catalogue for ordering the correct decals.
Tom
Tom View my layout photos! http://s299.photobucket.com/albums/mm310/TWhite-014/Rio%20Grande%20Yuba%20River%20Sub One can NEVER have too many Articulateds!
to those that replied;
THANKS! for your input and i'll print them to keep in my catalog of 'things to do sooner than later'.
texasccl2