The Milwaukee Road typically stenciled the classification of the locomotive on the cab. You can see part of the classification stencil on the 5057 below.
We plan to trace the stencil so we can recreate it when the 5057 is painted. The remaining part of the classification, the "RS" appeared to be missing. However, when we visited the 5057 last fall at the Pend Oreille Valley Railroad shop in Usk, WA we noticed it could be faintly seen under a coat of paint.