Are you talking about the aluminum inserts on the 81 Z28 dash bezel?
If so, you can buy new ones but they are expensive. A tad over $100.
I cleaned one up by using very fine steel wool and WD40 as a lubricant. It looked ok, much better than it did. If you can peel it off without kinking it and lay it down flat, it's easier to use the steel wool.
Someone on ebay is selling decals also, but wants about $50!
I believe the original finish was brushed aluminum.
Here's a pic of the new insert that NPD sells that I used on an 81...