Ford Ranger U-joint problem?
 

I have a 96 Ranger that started a loud ringing/rattling noise a bit ago. When I climbed under, There was a big metal ring loose around the U-joint. What is the ring and where should it normally be? And what need to be fixed/replaced?

I'm guessing that's your flange. Yeah, that should be tight. If it's what I'm thinkin of, you should have four bolts that fix it to the axle flange or the tcase flange. I can't think of any other "big metal rings" in that area.