There isn't one on here, and you may well struggle to find anything which has been kept up to date. 3.1.3 is simply too old now (this is important, as just because something once worked on 3.1.3 is no guarantee that it does today). Whilst I still use it on my iPhone 3G, you just need to be diligent when trying out tweaks.
The fact that it isn't an iPad firmware won't help in terms of looking for information on our forums here either!