Are your headlight lenses yellowed and don't want to pay $100+ for new ones. Try this simple process. Get some nail polish remover, a cotton rag, some plexiglass polish and a drill or Dremel tool with a buffing bit.
Apply a small amount of nail polish remover to the cotton rag. Wipe the lens with the wet rag. This will remove the yellowed, oxidized plastic. It will probably leave some white streaks.
Next apply some of the plexiglass polish the same as would when you wax your car. Use the drill or Dremel tool at a slow speed to polish the lens. I used my Dremel tool with a cotton attachment at the 1 or 2 setting (max 5). If you use too fast of a speed you will melt the plastic.
You should be able to see inside the lens again and your lights should be much brighter.
It took me about 30 minutes to do my 95 TBird and my 88 F150.
Apply a small amount of nail polish remover to the cotton rag. Wipe the lens with the wet rag. This will remove the yellowed, oxidized plastic. It will probably leave some white streaks.
Next apply some of the plexiglass polish the same as would when you wax your car. Use the drill or Dremel tool at a slow speed to polish the lens. I used my Dremel tool with a cotton attachment at the 1 or 2 setting (max 5). If you use too fast of a speed you will melt the plastic.
You should be able to see inside the lens again and your lights should be much brighter.
It took me about 30 minutes to do my 95 TBird and my 88 F150.
dollar store cheap tooth paste with "advanced whitening" and "tartar control" lol I bought it and a cheap tooth brush and went to town with it, than took out some windex and wiped it clean... tada... although they look almost "smoked" on the inside from age. I think they look good 
