Since nobody makes a higher class hitch for the 1998 Mercury Mystique the only option is a universal weld-on hitch. I recommend the Draw-Tite Ultra Frame # 41990-07. This is a Class V hitch with a 2" receiver and 7" tall brackets. We recommend taking this to a certified welder for installation. It is also worth noting that upgrading the hitch capacity does not increase the towing capacity of your vehicle. Although the hitch can handle 16,000 lbs you will still be limited by the max towing... view full answer...