I like to use this procedure as a good starting point for vibrations problems;
You can do as you like here, but I don't recommend rotating the tires first, because if you've managed to lose a tire weight you haven't solved the issue but just moved it to the rear. Just my opinion on this. And this is just me here. If I'm experiencing vibrations problems, it's going to my tire guy regardless for re-balancing and closer tire inspection.
1. With the truck on a flat surface, install tire blocks so that the truck can't roll forward or backwards. Put the truck in neutral, crawl under the truck. With your hands, grab the DL and move the DL back and forth at both in front of and behind the Center support bearing, taking note of any play in the Ujoints, and up and down noting excessive play in the center support bearing and the slip yoke as well.
If they look ok, look for signs of a missing DL weight here as well.
2. Check tires for problems, bulges cut's separations & missing weights.
3. If everything checks out good to this point, I'll take my truck in and have my tires re-balanced. Loosing a tire weight will throw them off real quick, causing rotational vibrations at varying speeds. Let the tire guy know your having vibration issues. He'll take note and check the tires for defects while re-balancing the tires. Also, ask him to show you the difference in all 4 tires, as far as how out of balance they were. Usually the place you buy your tires will do all of this for free.
If you do have to remove your DL for further repairs, U joints, Center bearing replacement etc.
*** Before you remove your Drive shafts***
MARK YOUR DRIVE LINE FIRST BEFORE YOU REMOVE IT. IT MUST GO BACK IN EXACTLY THE WAY YOU REMOVED IT, FLANGE TO FLANGE. TAKING SOME PICTURES OF THE DL FIRST NEVER HURTS.
Hopefully this helps you get it solved.