in either high school or college concert bands, i've seen actual brake drums being used as percussion. that is, the drum part of a drum brake system on a car. from the sound of the metallic clank in that song i'd say that's all it is. you can probably find one at a junk shop if you're handy with a wrench.
http://en.wikipedia.org/wiki/Drum_brake (there's a paragraph at the bottom about percussion use)
this is what one looks like...
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