[stangt00]

The 2 most common sizes you will hear talked about here are 3.73 and 4.10. The higher the number, the taller the gear is. The taller the gear is, the faster the engine can climb through the rpm range, but at the same time, it decreases your speed for each of those gears. For instance, with stock gears you can top out 2nd gear at lets say 65mph and hit 60 in about 5.6 secs. With a taller gear, lets say 3.73's, you will top out second gear at 60mph but do it in 5.2 secs. These are just examples. I used them just to give you an idea of what gears do and how the higher the number is of the gear you have affects yor mph and the amount of time it takes to accelerate. Also remember that the taller the gear you use affects your fuel usage. You will always use more fuel with taller gears.