I believe there are 6, 10mm bolts holding the rear reflector to the trunk deck. One on each end, and four in the middle (similar 4-point box to the license plate). On the inside of the trunk, There are possibly a plastic shell covering the bolts.
Giving the age, you may need some new weather stripping where the reflector meets the trunk sheet metal. So if you remove make sure you have some generic self-adhesive weather stripping available.
To prep, tape off the chrome (assuming not painting the chrome), and scuff up the smooth reflector. Don't use aggressive sand paper. Use 400-800 grit, or some medium steel wool. Clean up the reflector after sanding, wash to remove dust. Remove tape as well.
To paint, tape off with the chrome and black and anything you don't want painted with a painter's tape (blue). Get in a clean area. It's fall here and leaves/plant debris is falling already. Secure your work or have a steady surface for painting. Given reflector size, table and drop cloth to protect the table is my thought.
For promotor read the can. Most likely spray, and let part sit a few moments before applying primer or base.
For base also read your paint can, but most likely start with light coats of the paint, give time between coats (10 minutes). Two light coats, then get a solid medium to wet coat for the top.
Clear depends on your paint. Might need to let base dry for 24 hours to a few days, or you could lay down shortly after your base coat.
Pull tape near the edges before paint is dry.
Leave it alone for a few days, then buff/polish and wax. Install and post pictures!
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