No. The shock absorber mounts are not designed to hold the weight of the vehicle.
simply just replace rear shocks with air shocks or put spring lifters on the springs
Bad shocks. Your springs buffer car movement, but your shocks dampen spring action. If not for shocks, the springs would allow the tires to bounce and leave the ground (or dribble).
The shocks on the Town car are actually regular shocks front and rear and are separate from the air springs. They are fairly inexpensive. The rear has air springs rather than mechanical steel springs. Do not mess with them if they are working. Replacement air springs can be purchased from http://www.arnottindustries.com/ for around $100 each and they will last for another 10 years. If you can change spark plugs you can change an air spring. Arnott gives detailed instructions. Don't be afraid of the air suspension, it is much superior over the steel springs.
Lesabres only have air suspension in the rear, they will be a combination of air shocks with a coil spring on the lower control arm.
No , unless the spring is damaged
That would be the springs as long as the spring brackets aren't rusted in half.
The springs in the rear support the weight of the car, and give it a smooth ride along with the shocks.
Smaller and stiffer shocks/springs on the front, remove a leaf spring or 2 on the back and get stiffer shocks/leafs back there as well.
Yes the suspension is the same, they will fit. The springs have a higher rate and are therefore a little stiffer, as are the shocks. They will probably lift it a little due to the old spring being sagging from use.
Not necessarily. From what i understand, though, if you decide not to get shocks to accompany the longer springs, your ride quality will be a sloppy mess. If you have the extra cash, it would be best to get shocks that have more travel.
First, get new shocks and struts...on that vehicle, not entirely sure, but probably struts in front and back, no shocks. Check for coil springs in rear. If rear springs are coil, then struts. If rear springs are leaf, then shocks. While you're at the parts store, rent or borrow a coil spring compression tool. You'll need to compress the coil springs to remove/reinstall new struts. Other than the compression tool, standard garage mechanics tools will do the job.
They have air shocks in the back that are used for ride height control. This is not the same as an "air spring" system. They have regular rear springs and the air bladders in the shock are only pumped up when there is significant load in the rear, to prevent the rear end from sagging. This is a very simple and reliable system. Monroe makes great factory replacement rear air shocks and they are cheap too.