Rejailbreaking 3.1.3?

[looksandletters]

I'm selling my 3G as jailbroken/unlocked... but in order to get all my stuff off of it I need to restore/rejailbreak/reunlock. modmyi's jailbreak guide says that you can only jailbreak 3.1.3 if you have 3.1.2, and not from 3.1.3... so is there anyway for me to do this? I've heard that downgrading firmware is impossible on these two. Can anyone help? Either with re-jailbreaking or another option?

Thank you!

 

[Applejuiced]

3GS model.
What firmware are you on now?
Unlocked? Tethered or untethered?

 

[looksandletters]

3GS model.
What firmware are you on now?
Unlocked? Tethered or untethered?

No, just 3G. I'm on 3.1.3, 4.26.08 broadband. Yes unlocked, untethered.