How do I change my coupler from the new style to the old style on a EMD GP40 Diesel N Scale?
Why would you even want to use the older non operating knuckle couplersinstead of the newer ooperating couplers? You should just leave the more realistic operating knuckle couplers on it since it couples fine with the older couplers anyways. I can't see any logical reason to use the non operating knuckles.
Edit: I could possibly need additional information or clarification as to which couplers it currently has and which you would like to use. Are you wanting to use Rapido couplers?
I prefer changing the coupler on the first car rather than the locomotive. It's nice having a car with a different one on each end when messing with the train. I know that doesn't answer your question, but just a thought.