First of all, let me preface this by saying thankyou for your response I have always considered your posts to be very accurate and relevant even if not always well received when I read the forums for information.
A quick search makes that option seem unlikely

and not worth the effort involved.
I think I'll find a Hilux diff and chuck that in the back it seems like a G29 2/3/4/5 is 4.1 ratio and a A/B 03 abc are also 4.1 ratio (I'd think that would be close enough to 4.09 (difference of roughly 4mm per rotation of the 31" wheel) to not cause a problem and since 99% of my thrashing is rwd and I am normally being more sensible when climbing things it shouldn't be a massive issue. I am curious what you think about this option? if you are aware of any road blocks I might encounter.
Cheers mate.