Sargent couplers?

[Rscott417]

I just picked up an Exactrail bulkhead flatcar, I was looking over it to figure out how to change the couplers but there's no screw for them. I'm thinking it might need to be done by removing the screw that goes through the trucks. As I was looking it over I noticed that the Sergent couplers are compatible with these particular couplers that came with the flatcar. I still plan on changing them with most likely the extended shank, but I know it's been said Sergents will not work with any other manufacturers.