Where to find regulator tape or window assembly for '85 caddy

I have a 1985 Cadillac Eldorado convertible that needs a regulator tape for the rear passenger window, or (if I can’t find just the tape) a complete rear window assembly. The car is in the Houston Tx area. I’ve had no luck finding the part. Any ideas on how to find the needed part would be appreciated.

Go to google.com type in regulator tape and you will find some options such as
1985 Cadillac Seville Window Regulator Tape
$17.20 new - RockAuto.com
1989 Dodge Caravan Window Regulator Tape
$12.70 new - RockAuto.com

Still using Google, type in “used Cadillac parts” to locate the entire assembly…