Most likely you have 2.73. Do you have a fully loaded mustang such as leather, Mach 460, etc. then you will possibly have 3.27. My 98 GT has the 3.27 and at 70mph I am running around 2100rpm. If you running less then that you will probably have either 3.08 or 2.73. Also with the 4.6 I would go with the 4.10 gears. At first I was skeptical about that much gear in a NPI car, but I have ridden in some with the 4.10 and it is a definetly needed upgrade. Very streetable.
Like the others said, you probably have either 2.72's or 3.03's. I would go with 3.73's in a five speed pre99 GT with the stock heads and cams. Just my .02 cents.
Easy way to find out is to jack the rear end of the car up. Put a chalk mark on the top of the tire and one on the drive shaft. Have a friend, family rotate your tire one full turn, count the number of times your driveshaft rotates (use the chalk line as yout measuring point.) rotates 2-3/4 then 2.73, 3-1/4 then 3.27 etc. Go with the 4.10s!!!!
hmmmmm........interesting..........well damn then, 2.73s to 3.73s will be a nice jump, but like i said i still need to drive 4 hours to school and back in the fall..........
Like the others said, you probably have either 2.72's or 3.03's. I would go with 3.73's in a five speed pre99 GT with the stock heads and cams. Just my .02 cents.