How can I sync two Macs using an external drive?

[RonaldMacDonald]

I have a Mac at home and one at work. They are both Panthers and about 4 or 5 years old (still run great). The two machines are sort of growing apart from one and other as far as the data contained on each machine. Some is very similar and some isn't. Like I said, they are growing apart.

Is there a way I could sync them by using an external drive? I would not want to lose data in the process.

[MisterMe]

Synchronize! X Plus, Synchronize! Pro X, or Chronosync.