I have a 2007 Z71 Sub that has seen a lot of salty roads and what not. Parked on the street etc. I sanded that thing to death with I don't know how many different types of "grit". I gave up and spent the money....Basically went to CarID and priced things out for the model I wanted. I could have spent a lot, but went with OEM. All the brick and mortar car shops wanted way more with less service. It was a bit of jenga to get the new ones in as the old ones were really easy to get out with pretty much all of their plastic "pegs" breaking off due to age and brittle nature. I also had gotten to the point where I was replacing bulbs on the old and I think it had to do with how it was falling apart....sorry I'm rambling a bit here....