Excellent, thank you Mark. However, I was able to remove the tensioner without removing that bolt. I was able to remove the the other two bolts securing that plate, detached the power steering pump and leaned it aside, and then removed the water pump pulley which allowed me to rotate that plate up and down a bit enough to slide the tensioner assembly out of there.

Behind the tensioner (opposite side of the wheel) there's a silver circle with 2 flat sides through which the big 19mm bolt slides, and around that is a tight fitting connected with a loose screw (so it can move freely) to a shaft with threads at the top, and that shaft shoots through the accessory belt tensioner bracket. The Accessory Belt Idler Nut (using the terms of the shop here) is screwed on the threads at the top of the shaft, and that is actually what is going through the tensioner bracket. The 19mm bolt also goes through this plate when on the car, just to note.

On the old tensioner, the threads inside the smaller hole, through which the 13mm bolt (formerly known as the 11mm bolt) ran, were totally stripped. You can only see traces of threads, just a couple fibers. The 13mm bolt ran through the Accessory Belt Tension Damper, which was suspended on the other end upwards onto something else (can't remember, too lazy to run down to car). That damper is basically just a shock, and it didn't look like it was connected to anything else there, so I don't quite get how it plays much of a part in keeping the belt tight. I thought that bolt would go through a bracket with a smile line, and you would loosen the nut and move it up or down along the groove of that smile line to loosen or tighten, but I didn't find such a thing.

I still need to order a replacement 13mm bolt. I wasn't able to find it on this sites part, so I may put in a special order request. The project is certainly taking a teeny bit longer than anticipated.

A couple questions:

Are there any torque specifications regarding retightening the pulleys on the power steering pump and water pump pulleys?

Does anyone know of where I can access some diagrams, or pictures of the tensioner assembly? I did try the link Mike posted, and it looked like the same thing as the repair CDs I have, which I've found cumbersome to use, and I still haven't found much information on them regarding this tensioner replacement job. If anyone else has those CDs or is familiar with the site Mike posted, and knows where to locate the gem I'm looking for on there, please lemme know.