I'm looking for a set of drivers for a northern GS4
And a set of drivers for a4 8 4 plus war baby
A new engine is probably easier and better.
Definitely agree it will be easier to just purchase a new locomotive.
A major thing you have against finding the correct drivers is that you have to know the exact model of the GS4 you are looking for, there have been at least two that I know of, and possibly more. And the drivers are not interchangeable.