I'm a registered Apple dev, and I got a new phone. My old 3GS currently has 5.0 installed on it and I'd like to put 4.3.5 on it for testing apps under iOS 4. I've downloaded the 4.3.5 ipsw, and using Organizer in Xcode I can attempt to install it, but get the "The Device isn't eligible for the requested build" error. The phone restarts and goes to DFU mode.
Am I missing something?
You can download older versions of Xcode by logging into Apple Developer Connection Downloads you will need to be a member of the developer program to login.
Once on the site, from the Downloads section, choose Developer Tools – you will be shown with a list of all Xcode versions, back to 1.0 released in October of 2004.