I have 2 40 ' boxcars: one made by Life Like ( TH&B ) has rapido couplers and the 2nd one made by Intermountain has a "dummy" knuckle coupler ( made in 1 piece ). I would like to replace the whole trucks with Micro Trains trucks. MicroTrains has various types of trucks, such as Barber, Bettendorf etc... Which one should I get ? Trucks are fixed to the car with a plastic pin, but that plastic pin varies in diameter and size from one manufacturer to the other. Shall I use the original pin to hold the MicroTrains trucks, or does MicroTrains supply various pins and shims with their couiplers ? I'm quite confused about that subject.