That is the rear lateral link. Megan Racing makes adjustable lateral links, available in front and rear sets. You can find them on ebay.
o god..the rust...
thats not rust. it looks practically new compared to mine.
also it looks like the pressure from the sway bar? attachment is what busted it.
+1, that ain't no rust. You should see the undercarriages of our Montreal-driven Proteges. My 2002, which I've owned since day 1, and had treated with chemical rust proofing every year looks a lot worse than the pic above.