I don't know what horn hook couplers are, but on the newest set, purchased last fall, they are the easy mates and are attached to the trucks.

I have 3 Bachmann train sets, one is new the others are not.  The new set has easy mate couplers but the other two don't.   Can I replace all of the non-easy mate couplers with easy mate's?  It looks like all of the cars have short couplers, the caboose has long couplers but I really don't have anythng to compare them to to know which length I need to order.  Any help would be greatly appreciated.