He's probably referring to the 05+ swingers that are the single bolt for adjusting the chain unlike the 03-04. Z400 are great machines for sure! They do need a little clutch work on the hills though as the front end likes to come up a little (not to bad). Watch some of his videos if you have already not he is the z400 hill climbing machine !
http://www.youtube.com/watch?v=hFKdLPJcNHw