While driving I picked up a vibration, and it is most annoying. From time to time it is very pronounced, especially while under acceleration. My hope is it is some kind of failed mount, allowing normal drive train vibration to be transmitted to the body.

While it is most noticeable while driving, and this is very important EVEN IN PARK SITTING STILL, when I rev the engine its there.

At between 1700 and 2500 rpm it presents as a strong buzz that shakes everything inside the car, I mean the steering wheel buttons buzz, everything in the glove box rattles, even whatever is down in the vents makes noise now.

I haven't crawled under it yet as it started last autumn, and I just parked it for the winter, but tis the season and I'm preparing to embark on a diagnostic vision quest (gotta get it up in the air and crawl under and look around).

Any suggestions are welcome, I hope its something, anything, external to the engine/transmission, power does not seem to be affected, and out of necessity I've driven it about 500 miles this way. Wish me luck, and I'll make a full report to the bitter end as I work thru this.

 

I think your reasoning makes sense. Bad mounts. You never mentioned engine problem or transmission and for the "shake" to be there at standstill and between an r.p.m. range would be logical that it's shaking transference.

 

As I'm looking under the hood, I notice something funny looking about the AC clutch. It's got the friction portion rotating quite a bit off center. I only had a short window before the winter weather blew back in, so I didn't disassemble anything. I am hoping this will wind up being my vibration. I didn't have time to pull the serpentine belt to see if the vibration persisted without the ac spinning. More on this later.

 

That could easily be a tensioner, belt, or pulley failing.


A mount will do the same, but there will usually be a pronounced "clunk" when you idle back down.

 

Smooth as glass now. It was the AC compressor clutch. It had partially come apart, and as the images(If they uploaded correctly) show, there was a lot of mass rotating off center. I put the new compressor on and that was it, almost.
There was something more that wasn't related, but could have been contributing to the overall discomfort of the ride. As i'm crawling under the car looking for the source of an annoying little oil leak, I noticed one of the allen head screws that hold the front of the driveshaft on appeared to be missing.
That's right, the head was gone, however the threaded part was still sticking thru just like the other 5. Fortunately(the word of the day by the way) I was able to spin the broken part on thru with my fingers. THAT is when I noticed that the screw next to it was about an eighth of an inch loose so I removed it also, so I could easily match a new bolt. After much searching(Thank you Fastenal for having 6 of the exact bolts I needed all for only $6.75) I bought all new as these are not recommended to be reused.
Here's the lucky part, I was able to remove not only the broken bolt with my bare hands, but the eighth inch loose one as well. Not only that, but the bolt on the other side of the broken bolt was backed out as well. Not only that, but I was able to remove ALL 6 driveshaft bolts with my bare fingers. Of course I was replacing them with new ones one by one as I removed them.
If I hadn't needed to get under that car, or if I had continued to drive it,( its been parked for 6 months because I didn't want to tear anything up until the snow went away, and I could look at it) something bad could have happened.
So that's my story. I hope someone gains a little insight, and is able to avoid a catastrophe by maybe thinking to periodically put their cat on a lift and taking a good look around.

 

Woof!!