So, I'm still making progress on the newly-acquired Signature Limited. I discovered the water leak from under the cowl early on, with the puddle in the rear passenger seat floor.. right
after I bought the car and saw that info on this forum. I got it dried out, and with the great help here and on youtube, it went through the car wash 2 days ago without any more drama. (I did leave the carpet lifted up with a folded towel on the floorboard just in case, to catch any water that may come through, but it was dry. I'm thankful, and everything is back together.)
There were two little wet blobs of what seemed to be the old foam gasket that blew out from the upper a/c vent right after the car wash, but hopefully, that wasn't more than a one-off event. I do remember seeing something about a foam gasket on an a/c door, but I can't find that now. I also checked under the front carpet on the drivers side for any leakage from the hood release cable, but it was dry as a bone. I will assure that the cable is well sealed where it comes through.
I was also struggling with the black hold-down 'nut' that is on the engine cover above the alternator.. it was seized and it took many hours of effort to finally get it off. I had to drill it out and grind some slots in the top of the nut so I could tap it off. It was on an M6 stud that went down into the throttle body extender, and would normally be removed with a 1/4" extension, but that had become cammed out.. I think it was prettier than it was functional, so I chose to replace that stud with a M6 - 50mm hex bolt, and I used a washer and wing nut on the top. Not as sexy, but drama-free. I could have also used a 35mm or 40mm bolt and kept the original black nut, but I decided the wing nut was the smarter choice (however, the black nut will be in the glove box if the next owner disagrees..
With 101K, I think the spark plugs are the next adventure.