ford explorer rear vibration

[gregmoneyp1]

i have a 2001 ford expolrer and it has a vibration in the rear end at 65 mph

 

[FordGT55]

Have you tried to rotate the tires to see if the vibration moves or goes away?
things to check:
Tires to see if they are worn unevenly
Tires in balance?
U-joints, are they worn out?
Fluid in the diff low / leaks?

Is there any noise or anything other information you have?