how to check a worn drive pinion bearing

[nh98gsx]

so i have been getting a moaning, vibration from the rear of the car mostly in 4th gear at 2,500 rpms, in VFAQ it say that it is a worn drive pinion bearing, is there any way to check that with out pulling the whole the rear diff down, and if that is the problem how the hell do you fix it.
Thanks,

 

[nh98gsx]

so i have come to the conclusion that i will have to drop the rear end, does anyone know how to replace a worn or loose drive pinion bearing.