Broken down, need diagnosis.

[Puyallup68C20]

At first it seemed like any night leaving work, but at the light to leave it feels like my tranny slips out of gear and gives me a loud metal chinking noise in drive reverse or park if I give it gas. So I put it in neutral and coast back into my works parking lot, all the while with little clanks going on. With what little knowledge I do have I figured it was driveline related so I get a flashlight and get under the truck and find my "middle" U-joint is extremely loose and wobbles every which way. Did the U-joint Fail? Or is it naturally that way and I have broken something else? Ideas / suggestions gladly accepted!