how to upgrade from 3.1.3 to latest with 3g?

[beachy1]

hi!
i have a 3g version 3.1.3 05.12.01 firmware
i was wondering how i can upgrade to the latest version of the iphone.
if anyone can recommend a website with a tutorial please let me know . i have been looking online but i cannot find one that matches the same version i have...
thanks

 

[WhatAmI]

hi!
i have a 3g version 3.1.3 05.12.01 firmware
i was wondering how i can upgrade to the latest version of the iphone.
if anyone can recommend a website with a tutorial please let me know . i have been looking online but i cannot find one that matches the same version i have...
thanks

http://www.iclarified.com/unlock/iphone3g/os.php?baseband=05.12.01&firmware=3.1.3

Just choose your preferred operating system

 

[Applejuiced]

Do you just want to update to stock 4.2.1 or maintain your unlock and jailbreak?