Even though I drive a YJ, my driveline is from a '98 XJ (4.0L, AW4, 231). My front axle is also out of the '98 XJ (D30 non-disconnect). I have an 8.8 out back too.
I was getting 10 mpg (city) with 4.10s and 35's. Last weekend, I regeared to 4.88's, and I am now getting 14 to 15 mpg city...