I am in the process of replacing the shocks on my 99 Grand Marq GS...only 53k miles but those shocks have been on there for 14 years. The car is riding ok overall but feeling like it may float off the road on severe bumps. My friends have a 2001 Crown Vic with about 40k miles, and recently replaced their shocks - they told me that our mechanic (who is top notch) had a hard time because they were so rusted in place and ended up doing some damage in the process which he of course made good on. So I went to Pep Boys, where they do a lot of this kind of work. They have a special on Monroes, it is coming to about $250 with installation and tax for four Sensa Tracs. Sure enough, they encountered problems. The rear shock bolts are firmly rusted into place, and being Sunday afternoon no place to get replacement bolts if the old ones break. So we installed the front shocks today and will return to install the rear shocks later in the week. The ride is greatly improved with the new front shocks, slightly firmer and hold the road much better.