i am trying to help out a friend, so i want to make sure i am doing the right thing and not brick his phone, so i thought i would come to the experts for advice since you guys have helped me so many times before :-)

he has a 3gs, baseband 5.14.02. i know that that baseband is not unlockable, so when i went to do the baseband upgrade in redsn0w, it said i should not proceed if i had the new bootrom. i've been through that before as well since my partner has a 3gs as well, and i have jailbroken and unlocked it for her. what i am not sure of is which one he has. i know i am supposed to look at digits 3-5 on his serial number and they are 939. i think i read that the cutoff is week 35, but i am wondering from what year. if i read the info correctly, his phone was manufactured in week 39 of 2009.

i didn't proceed with the bb upgrade, but he really wants to use the phone on simple mobile, so i want to be sure before we go any further.

thanks!