WD-40...... Start by spraying/soaking components one at a time and driving!... When the squeaking stops... That's where you need to focus your repair!!!!!... Don't go throwing unnecessary parts at it, find the squeak first!!!
RepairPal Certified shops can diagnose and repair your 1998 Mercury Grand Marquis. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.