There's many ways of restoring plastic lens' but this is my quick and easy how to. These are reproduced now and after I get new paint on the car, I'll buy new ones. I just wanted to get the car driveable and wanted my lens' visible so I don't get rear ended. These are for my 87 SS Monte Carlo but this process should work on any G Body tail light. They are dull, scratched, bird crap stained, and the back up lens is yellowed. I started by soaking them in Dawn dish soap and hot water in the kitchen sink. This will soften up the strip caulk holding the lens to the backing and loosen dirt/dust. I used a very small flat blade screw driver and popped off the emblems. There are 4 bendable tabs that need flattened to remove the lens. I used a medium sized flat blade screw driver and slid into the strip caulk. I slowly and softly worked it loose. If you give it just a slight turn of the screw driver you can see it start separating in slow motion. Take your time and don't pry against the middle areas. This could crack the lens. Stay in the corners. After they're apart, clean off the old strip caulk. It won't all come off completely and that's fine. The new strip caulk will stick anyway. I used a tooth brush and soapy water on the back side of the lens to get the dust out of the ribs. I then sanded the outside of the lens with 1500 grit wet on a very soft sponge block. It will remove light scratches and remnants of the chrome stripe around the lens. My chrome stripes were almost gone anyway. I rinsed it, dried it, and placed the lens on a towel. I use Mothers mag and aluminum polish on a microfiber towel. I like the microfiber rags for everything I polish. I hand polished with good hard pressure in a circular motion for a few minutes. I then used a different section of the rag and put on more Mothers and polished one direction.(up and down) for a few minutes. Going finer on your sandpapers would probably be fine and a mini buffer would work better but this was just fine for a temporary restoration. I flipped over the lens and only polished the back up lens side to side with the little ribs in them. I then washed the lens again and rinsed. I used an air blower on my air compressor and blew around the edges of the clear backing lens and red tail lens. It got all the water blown out so it don't dry spotty between them. I also blew out the outside of the back up lens edges. There is a tiny gap all around it that Mothers had collected into. Some did not blow out so I tooth brushed the edges. I will clean and re paint the back that the bulbs go in with chrome spray paint. They have faded to gray so a new reflective coating is a must. I like Valspar Chrome spray paint from Lowes. It goes on great and is very reflective. I will re strip caulk them and use a 2 part epoxy on the emblems to reattach to the lens'. The 3M strip caulk is available at my local O'Reilleys or any automotive paint shop will have it. I'll also repaint the gray on the outside edge of the lens. It is raining today so no painting for me. I hope this helps some of you guys in the future. Again, this is just a quicky job I did. It could be way better but going with new ones after car is painted.