I don't know of any 1998-2000 XC70 videos. Yes, the calipers are weird, but not rocket science to understand. The 2 slide pins still need to come off, cleaned and re-greased. The pads are unique, they have little spring things on the back edge.

What I have done is first, release the tension on the ebrake cable by opening up the trap door under the center armrest and spinning the tensioner clockwise.

Always remember, the rear wheels can be turned going forward only. Moving the rear wheel rearward will lock it up. And hang the caliper from the springs and not the flexible brake line.

"Bob is the car guy" uses silicone paste as a grease agent. It is high temp and water resistant. You can also use a dab of paste where the hub and rotor touch, and where the wheel and rotor contact each other. If you cannot find the paste, get a small tube of silicone brake grease.

Be careful removing the rear rotor. The brake shoes can create a groove in the rotor making it difficult to get off eventhough the rotor is loose.
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Keeping it running is better than buying new