I have an 86 trans am. I have noticed that over the years, my back end has begun to sag more and more. I can even tell a difference between how much it sags when there is a full tank of gas and an empty tank. What is it that needs to be replaced to get rid of this sag problem? Does my car have shocks or struts or both? Do the shocks or struts need to be replaced? Or is it the springs that need to be replaced? Thanks for your help!

Our cars have a modified macpherson strut in the front and shocks in the rear, however it's the springs that case the rear end sag. Now would be a good time to replace all of the springs and if you have the money replace the struts and shocks as well. Many people on this board like the KYB shocks&struts and Eibach prokit springs combo. Do a search see what fits brand your needs.

You need springs.

Go to any real parts store, that carries Moog, and order yourself up a pair of CC635 springs. You can put them in yourself in the driveway. All you have to do is jack the rear of the car up, put the frame on jack stands right where the lower control arms attach to the body, take the lower shock bolts out of the rear end, and let the rear end hang down; the old springs will fall out. Then just put the new ones in and put the shock bolts back on. It would be a good idea to get new shocks at the same time, but they don't hold the car up, they control the up and down motion of the body.

Awesome, thanks a lot for your help guys! I don't have an impact wrench, do you think that I will be able to break the shock bolts loose without one? I really should invest in a good compressor and impact wrench, it seems as though I need one more and more!

No, you don't need air, a ½" ratchet should work fine