Before shot of tail lights from Pick and Pull.
they were in decent shape, just really oxidised.		 After cleaning and polishing with a polishing pad on my Dremel tool and Mothers Aluminum Polish.

 

Mothers state on the container and on their website that this shouldn't be used on plastic. But I've used their product to polish plastic tail lights and headlights on my cars and motorcycles for years, and it hasn't harmed any of them.