How long have you been jailbroken? You know, you might have your blobs saved in Cydia. Also, if you haven't done anything, and you're still on 4.3.3, you can use iFaith to dump the 4.3.3 blobs, make a pre-signed and pre-jailbroken firmware, and restore to that! I got a white iPhone 4, with 4.3.3 installed on it, when 4.3.5 was the firmware that Apple was signing. I used iFaith and it worked great!