If it's still there, they should have a tag on them for right and left; REB or LEB (i think the middle letter is and E on mine..) If not it might have a different letter, but if there's a 'B' on it, thats your bar If not, you might be able to look on the ends of them, where they go into the lower arms OR on the frame mounts, I think it may be stamped on the ends.
EDIT - Found the stiffness codes in order: B D E F G H J L .. There's been some talk about code 1 and 2, but I don't think anyone has really ever seen them, but if you can find a 1 or 2, they're said to be the strongest, but I can't say for sure.