Vibration at 25-35mph and light load and at highway speeds - getting worse!

[Boringchuck]

2000 Outback 130k new to me.
It didn't have vibration when I boguht it 500 miles ago, now it does.
It feels like judder from 25-35, but there's also vibration at highway speeds.Also, it lightly 'clunks' (that I can feel more than hear) when the gas pedal is let off of then put back on.
The highway vibration is getting worse.

I added the magic goo (Lubegard 19610 Instant Shudder Fix) to the tranny 100 miles ago - no improvement in the vibration from 25-35 mph.

I'm thinking it may be the driveshaft carrier bearing or its rubber mount (but 130k is kinda low for that I'd think).
My question is: how to diagnose that without pulling the driveshaft. I had the car up and crawled under and pushed up and down on the driveshaft and it moved rather easily - I don't know if the rubber mount should alllow easy movement or if it should be stiffer, it just seemed rather soft to me.

The tranny mount just got replaced by a competent mcechanic. 

Any see-through-brick-walls folk out ther who can diagnose from a distance?
: -)

Thanks!

[lmdew]

Put the FWD fuse in and see if it makes a difference.

[el_freddo]

Check your tyres for a bubble or something odd. 

I went through a process of eliminating parts from the back of my L series including removing the rear diff and driveshafts! Turned out one rear wheel developed a small bubble/egg on one side of the tread. 

Swapped the wheel and happy days!