Yep, axle shaft bearing. Need a slide hammer w/ puller attachment to get it
out, I used a large hammer, small 2"x4" block, and the old shaft bearing
race to reinstall. Had to rebuild the rear on my Ranger last month. Same
basic parts except the axle shafts and housing aren't as long.
pretty good diagram here if you search out the part:
http://www.fordpartsonline.com