iphone sdk 4.3 question

I have a question regarding iphone sdk 4.3. I recently purchased a macbook and am trying to get it working with Unity3d.

I signed up to the Apple Developer and downloaded the available SDK.

Posted: March 24, 2011 Snow Leopard Build: 10M2518 Snow Leopard Downloads Xcode 3.2.6 and iOS SDK 4.3

But now in Unity there is only the option for 4.2 and after I publish, I get an error in XCODE error: There is no SDK with the name or path 'iphoneos4.2'

So Since I downloaded SDK 4.3 I assume it's cause I don't have 4.2. Now I'm trying to find 4.2 on Apple's site but I'm having trouble locating it.

So my problem is just not having the correct SDK I assume.

Can anyone help?

Thank you