No problem, it's an easy swap. Depending on what car it is, you may have to destroy the 2-rail coupler box to remove the body-mounted coupler. Some of the newer molds make it easy to remove the coupler; on the older ones the coupler box snaps into place when it's installed and it's all but impossible to get off without cutting it. The Atlas tech told me he always cuts them off, doesn't try to salvage them. No real problem when you go to sell or swap off the 2-rail trucks, the coupler mounting boxes are available from Atlas, they are cheap, and any 2-railer who's buying trucks and couplers from conversions will have a pile of them on his bench.