Used or refurb is your only option unless you go to a full aftermarket cluster for $800-$1000.
1998 is a specific one off year so you will need another 98 cluster or send yours for repairs. Then you will need to get PATS disabled or have the cluster keyed to your ECU which only a Ford dealer will be able to do.
2000 Mustang GT Steeda build #48. Bolt ons, suspension, Novi 2000.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.