Time-sensitive iPhone 3G 3.1.3 unlock question

[N10do64]

I have two iPhone 3Gs running 3.1.3 and BB 5.14.02(due to being upgraded to 4.0 then back down), is there any way I can unlock these without upgrading back to 4.1/.2? These are iPhones that have been sold and delivered to eBay customers,so I have a time limit.

[iYeow]

You have to go with ipad baseband if you want to unlock it.

[N10do64]

Can redsn0w do this to 3.1.3? And will ultrasn0w/redsn0w unlock work on 3.1.3?

[belebartok]

For 3g, I think yes. For 3gs and 4 it would not work. 3g you can put any fw you want.

[N10do64]

Could you point me in the right direction for redsn0w for 3.1.3? Isn't that .92 or something like that?