Anyone know the correct # KayDee coupler to replace the ones that are on the Bachmann On30 passenger cars ? The knuckle whiskers on the supplied couplers are failing and I'd rather replace the couplers with metal KayDees rather than hard to find and just as likely to fail again Bachmann couplers. I no longer keep a collection of the various varieties of KayDee couplers around since I'm mostly large scale these days. I'd rather not order blindly guessing at the correct one.