When replacing a starter on a 1991 sundance does anything else need to be replaced?

No, only if other problems are evident such as: You may have to change the starter cables, battery cables, or cables at starter relay (if equipped). these cables may be frayed, corroded or loose ends. not sure if that year starter has a selonide located on starter frame, or relay. you may have to take away shims between starter and mounting surface for proper alignment of pinion gear, and fly wheel, or sometimes add. May have to possibly change battery if starter drained it too much. Starter relay may have to be changed. selonide usually comes attached to new starter.