One problem related to rear suspension has been reported for the 1998 Subaru Forester. The most recently reported issues are listed below.
My 98 Forester had the right rear bearing changed 3 times by non dealer chain. Started making noise again. When I went to Subaru, the mechanic told me that it's common. He has been replacing them with legacy bearings and has not had any complaints. Also the vent on top of rear differential blows or sweats diff fluid out onto differential. Potential for freeze up of differential once all fluid is gone. Mechanic claims he would have to open differential and "notch" some metal guard in there to prevent this. This along with bearings-$600.