http://www.mazdatrix.com/8-Diff.htm
^notice the 3.909 gear.
http://www.mazdatrix.com/getprice.as...m=27-110A-P062
^notice it says 93-95 + Rx-8. (says this for all ratios actually).
http://www.mazdatrix.com/g5.htm
^Notice at the bottom. 93-95 AUTOMATIC has 3.909.
Now that I think about it, I sold a Rx-8 R&P to a FD guy who wanted a high number gear. So there ya go.
Obviously, cheap option would be to find an auto FD used diff, and swap in ring and pinion. New, especially from mazdatrix, will be quite spendy.