Q&A

 Master

Is the pinion bearing bad or is it one of the carrier bearings? It looks like the pinion bearing is pressed on. You'll need to check your pinion depth when reinstalling and inspect gear mesh. It's always a good idea to check backlash and the mesh pattern again.
You will need a dial indicator with a magnetic base to check backlash.
http://www.corral.net/tech/drivetrain/gears.html

Lots of good reading here as well.
http://www.explorerforum.com/forums/showthread.php?t=144780

good luck!