Is there any reason to keep deteriorated bucket seat backs and aprons? In this specific case they're white and badly deteriorated. I hate to throw anything away, but these seem hopeless! Sorry, but I'm getting an error message this a.m. when trying to upload any photos, but I suspect most readers will know what I'm talking about.
Sometimes I keep those parts. I call them BTN parts- better than nothing! Good parts for a beater. Sometimes even scrap parts can provide you with a piece of plastic that can be used to make a repair on a better part. I make my own glue with scrap plastic and acetone. Before you throw them out, put them up on the board for the cost of shipping.
U can run them thru a glass bead cabinet at low pressure and an upholsterer can cover them in vinyl. Glass beads will remove the chalky plastic. I give my old ones to my upholstery guy