Take your new angle gauge and set it either on top of your shaft or up underneath your shaft. The reading on the gauge is your driveshaft angle. Now remove the shaft itself. Rock the vehicle a little bit until the mounting faces of the two yokes (pinion and transfer case output) are both vertical. Now set the gauge on the face of your rear differential pinion yoke. This will tell you how many degrees up from horizontal the pinion is pointing. Now set the guage on the face of the Tcase output yoke. This will tell you how many degrees down from horizontal your Tcase is sitting. When everything is working and in balance, these two angles need to be the same for there to be no vibration.
In a static situation, with the vehicle not moving, the rear differential pinion should be one or two degrees less than the transfer case output angle. This is because as you start moving and applying torque to the driveline and consequently the springs, the rear differential will "wrap" or strain upwards against the torque a little bit, thus increasing it's "up" angle (as measured from a horizontal line). When the wrap is happening i.e. you are driving down the road, that is when you want the angles to be the same, as opposed to when you are not moving and the driveline is not under any pressure.
So, what is your driveshaft angle? 18 degrees may be at the upper limit for a conventional shaft; I can't remember, and I think someone (Wayne?) posted the number in one of your earlier inquiries on this problem. But first try measuring and correcting the pinion and Tcase output angles.
And I didn't read all your earlier posts; are you sure it is a driveline problem? An out-of-balance wheel can cause vibration, sometimes felt only at certain speeds. How about the driveshaft itself, could you have knocked a weight off, or dented it minutely, throwing it out of balance? Did the vibe start all of a sudden, or has it been present since you've had the vehicle? More than once I have gotten all caught up in a complex problem only to find that it was something simple that I overlooked.
82 CJ, some stuff stock, some stuff not
Have you hugged your Jeep today?