Yesterday Saurik updated the tool on the home page of Cydia, which retrieves and saves the ECID of our 3GS iPhone so we can downgrade at any time. Eagle Eyed folks at iSpazio noticed the change according to them, until a few hours ago, on the opening page of Cydia receive a message that only the first version of the firmware that had been saved ECID (first screenshot), but now are clearly displayed all versions of the firmware can install on your iPhone 3GS (second screenshot). If you aren’t aware of ECID, Cydia SHSH then read this article to understand what ECID is and why you need to dump your Signature files.
>>>>>>>> Before <<<<<<<< >>>>>>>> Now <<<<<<<<
For those who are unaware with the SHSH thingy, this is due to the fact that Apple prohibits iPhone 3GS users to downgrade to previous versions. But if you have already saved you can install the firmware you like and forces them to keep only the latest version. With this detailed guide instead, all people who have saved the ‘ECID can downgrade by installing an older version of the software.