Good news - I've positively identified the source of my problems. The new accessory drive parts are in, and with the additional tension the noise is now constant. Sounds like the bearings are shot on the alternator. Been trying to remove it, and this is one of those jobs that I'd like to meet the designer on. I'd either like to see his 1 inch diameter arms with 17 different joints that all swivel 360 degrees so I can see how easy it is for him to do this job, or arrange for him to have 17 different joints in each arm. I shoulda had this damned thing out by now.
Looks like the top bolt is a male torx head, and of course I have no female torx head drivers so after I get cleaned up I have to go get some, then let the car sit until next week. I'm glad this isn't my only vehicle. And, can anyone clue me in on how to get the electrical plug off the alternator? I can't see the thing, and can't tell how it comes off by feel. It feels like they used a hidden catch connector on it, then made sure to rotate the catch so it can't be seen.
Incidentally, the idler pulley Rock Auto sends is Goodyear pn 49001, which is too large in diameter. The local parts store sells the same pulley, saying it's a superceded part. They matched my old idler pulley up to a Gates pn 38006, and gave me a bushing since it didn't look like it would fit right. I cut the bushing down so it would fit along with the bolt that has a built-on bushing, then added a washer between the bushing and the mount point. Works like a charm. If you decide to use the larger idler pulley, you will need a belt about an inch longer than the factory belt. Not sure exactly how much longer since I'm not using it, but I'm guesstimating an inch.