Found the Gauge looking for an answer. I'm a once a year RRer( Christmastime) and it's coming fast. I need it running for Grandchildren. My setup is a 4x8 plywood around the tree and thru my wifes Dept 56 villages. I bought a PA RR Mantua set 25 yrs ago and bought a better engine Stewart Hobbies(Kato?? on inside) I've had trouble with the couplers and decided to replace all with the universal Kadee.Just found out that the engine requires a Kadee#35 short 1/4in overset which I ordered and about 5 Kadee#5 Universal couplers assebled. My question is on the cars , do I just attach them to the metal extending from the truck by the right size screw or should I look at replacing the trucks.