You definitely won't find an OEM ratio that tall, and all the aftermarket centres I've seen are low ratios (like 4.1:1 or lower).
The only thing I can suggest is a MkIV Supra; the 6-speed TT models have a 3.2:1 ratio and the later versions have an A series diff which is apparently compatible with the G series (eg Hilux). If you can find one of these for sale it might work.
The tallest diff centre for the hilux is 3.54.So I am told Which is what I intend to use for now.I still have to find out what model it comes out of and where I can get one.
Why do I want a 3.08 ? The Ute is to be powered by a Vn V6 and Vn Auto and thats what they run. This runs about 2000 rpm @ 100kph.