Look at the last six digits of the serial number. Every 5000 is a model year change. So anything between 680XXX-684XXX is a 1999. Anything 685XXX-689XXX is a 2000. For example a serial number of H00925F680331 is a model year 1999. If it were H00925F685331 it would be a 2000. If it were H00925F691222 it would be a 2001.