Mystery vibration at 25 mph can't be diagnosed. It's not the front end!

Anyone check all the engine and trans mounts?
I wouldn't rule out the ujoints unless I pulled the driveshaft and felt the pivot of each joint myself.
They can get dry and bind up without feeling loose, and 25mph is about the perfect speed to cause a shudder you can feel.
I would almost put money on it being a dry joint.

"10 days"?
What the hell?