In my Cave, Brake Service I covered this topic but Didn't have real pictures for Where or Why.
This should show you better.

For 84 to 87 Calipers and the Mounting Brackets... Shows Left Rear out of the car parked for Years but all are the same.

CLICK FOR FULL SIZE

Use a very thin coat of Brake Grease like Permatex® Ultra Disc Brake Caliper Lube. Not Silicone or any other kind.
Also do the same for the Top and Bottom of the Calipers. Only coat them wide enough area that calipers slid in/out along the "Load ears."
Brake Grease won't wash off easily and interferes with Galvanizing the metals causing heavy corrosion.

Why?
To prevent this damage...

CLICK FOR FULL SIZE

Is the Top of the Caliper and the "Load Ear" on the bracket to stop the car going in Reverse.

CLICK FOR FULL SIZE

Is the Bottom of the Caliper and the Big "Load Ear" on the bracket to stop the car going Forward.

CLICK FOR FULL SIZE

Is the Bottom of the Bracket for Load Point for the Inner Pad to stop the car going Forward.

The corrosion contains Aluminum Oxide that is used as an abrasive for Sand Paper and Grinding equipment. I've seen worse aluminum caliper below w/ alignment problems because of big "Load Ear" grounds the caliper unevenly. So If an outer pad has one side worn down more... this is likely why.

CLICK FOR FULL SIZE

Front caliper shown here and installed dry. Notice even the small wear issue here is uneven cause uneven pad wear and binding when brakes are applied.
The wear in that pic is from a few issues... Mainly Parts get Galvanic corrosion from driving in rain, on road salt, etc. then they grind on AlOx in the corrosion as the brakes are used.

Yes... They seem to be minor but even minor problems often causes obvious Brake Problems and Poor Brake Performance.
Plus the Sliders need Brake Grease as directed in many GM FSM and My Cave. Use enough grease to fill the gap between hole wall and the slider but don't get sloppy so a lot of excess grease just pushes out and waste it.

Before you ask... 88 Sliders are a different type but needs Brake Grease too. Lube areas that touches Pads metal edges too.

Side Note: These images posted by new Upload Image button then edited to make them [img thumb] Full size is Dynamic Size to fit a window etc. Size here is only 762 x 744px in PNG format. Why? I have a big screen but don't want big pictures all the time. I doubt many small screen users want big pics all the time either.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave