Welcome to the forum!
Yeah, that old rear window seal (window trim) turns to what we commonly refer to as 'lasagna' when the trim has been exposed to sunlight after many years. Most owners just live with it but some get creative at hiding the wavy rubber seal.
John Temple, a member here, sells a rubber window trim kit as a way to improve the looks on your old, wavy window trim. It costs $60.US not including shipping. You can purchase it directly from his website (templeperformancecars.com) or from eB*y under 93-98 Lincoln MarkVIII Window Trim Repair Kit. There is a couple pictures there where you can see how the trim looks like after it has been replaced with the kit.
You can also call his shop near Atlanta at (770)722-2587 from 9am-5pm EST.
The kit is for replacement of the lasagna perished sides only and it is not for the entire upper and lower rubber trim.
