I need to know which wire to connect to which.  the connectors are different and the wire colors are also, when replacing a new Bachmann motor blk into an older aristo craft UB25.

Received a broken saddle tank loco from a friend.  would like to replace the gear that is no longer there.  Since the chases is dis continued at Bachmann I looked up the part on their diagram. G113X-00D01.  Does anyone know of a gear to replace this one with