Problem solved. I just needed to move the parking brake lever out of the way using vise grips on the lever to pull it back and out of the way so I could access and remove the upper caliper mounting bolt.
I lifted the caliper up and out of the way so I could install the Centric kit clips onto the caliper mounting bracket. Success! No more rear brake rattle. This was especially noticeable with the top down on my 1990 convertible. With the top up and windows closed, the rattle was not noticeable. But top down...UGH, that rattle was super annoying!
If your Reatta has an annoying rattle coming from the rear, chances are it's the replacement brake pads rattling. The Centric kit comes with other parts I didn't need, however I replaced the upper and lower rubber boots on the caliper bracket as well since they were exposed and easy to change. The upper and lower clips are easy to insert.
Centric PN 117.62026 available from several vendors including Summit Racing. I paid $17 from CARID