My 08 Rev 3 has developed an odd squeak. It sounds like it comes from the bottom rear of the skid plate. It happens when holding the rear brake and pushing down/ forward on the suspension. No matter how or what I try, I can not create the squeak with out the rear brake on. I tried a little penetrating oil around the shock bearings and swing arm bearings with no affect. Has anyone had this?

Check and see if the shock is rubbing on the airbox. Sometimes after a more creative line selection the aluminum bracket that holds the airbox on gets bent enough to allow the shock to rub/squeak. If so, some "persuasion" with a rubber mallet will cure the issue.

The lower shock bearing is dry and crusty so I assume that is the issue. This does not appear to be a standard size. Could it be a Beta only bearing? 14 x 26

It is. It's also a bit different from anything I've run across in that there are two collars that press into the shock eye itself. On mine, te best way to get them out was to use a blind bearing puller that fixed in the collars and straddled the shock body itself.

Try squirting the oil around the back of the skidplate where it mounts to the frame. A lot of times the frame flex will loosen that area up and it will squeak. It's probably a good idea to go round about the frame and snug things up if you haven't done it for a while.