Ford Focus: 2005 zx3: clunking sound?

Hi -

I just bought a rather stripped-down 2005 Ford Focus ZX3 - all it's
got is AC in the way of extras. It currently has about 700 miles on
it. Over the last week or so, I've been noticing a kind of clunking
sound coming from the left rear corner of the vehicle when I'm driving,
particularly if I'm on a dirt road or going over bumps. It sounds like
it's coming from the left rear wheel well, but it *could* be the rear
seat latch. Maybe it's been doing it since I bought it, maybe not - if
there's any sound in the car (stereo, road noise, etc.) I can't hear
it. Question is, has anyone experienced this? Anyone know what it is?

Thanks -

Matt

yeah, I think I figured out what it was. I don't know how earlier
models of the Focus work, but when you fold the rear seats down, you
need to first fold the seat cushions up (the part you sit on in the
back seat), and then fold the back rests down. The cushions that you
sit on in the back seat (just being overly specific here so you know
what I'm talking about) have a metal shield on the underside, so that
when they fold up, there's a metal shield between whatever's in the
expanded trunk and you in the front.

I think it was the metal of the cushion's underside bumping against the
metal body of the car that was making the sound. but it should have
some padding there, I think, 'cause it's loud and annoying when the
seat's up.