Do you have an auto or a 5 speed tranny? Go with 3.73s for the 5 speed and 4.10s for the auto. This is for the daily driver. Go steeper on the gears for a strictly drag car. I've got the 3.73s in 5-speed and love them. I still get great gas mileage. Low 20s on the highway and your in town mileage will also improve and it'll drop a few tenths off of you 1/4 mile. It took .4 off of mine.
------------------
1996 Mustang GTS For Sale:$10,500