I believe in the US, if a dealer has to replace one, they send both the new one and the old one off to some place where they make them match.
Your best bet is to try and get a cluster with matching mileage.
Also, you can't just bolt in the cluster and go. The car will not start because of the PATS system. You have to find somebody with an NGS and have them relearn the keys, or get a chip or flasher to turn off the PATS system.
This all applies to 99+ electronic odometers. 98 will still have the same problems with PATS but you can adjust the dials inside.
2007 Shelby GT500 705RWHP/708RWTQ
2000 Mustang 3.8 A4 TT 450RWHP/475RWTQ 10.996@127 17psi stock 3.8
2006 F250 CC 4x4 6.0L 14.3 @ 93
2006 Mustang 4.0 M5 Vortech 13psi 395RWHP/374RWTQ wife's car