Rear Wheel Clank

Chevy Sprint 87'. Getting a rear wheel CLANK sound when I back up. If I stand outside of my car and rock it back and forth side ways, the left rear tire clanks.......Possible problems? been at it for a good 2 hours and have yet to see anything..thx guys.

  Devon1299

1st thing I would do , is to check the lugnuts.

  lectroid