I assume you're talking about a manual trans ... pretty sure the auto comes with 3.73 by default.
That number represents the gear ratio in the differentials. A higher number means more torque to the wheels, but it also means your engine runs at higher RPM's when cruising on the freeway.
If you ever plan on towing or running 32" tires you want it. If you're going bigger than 32" you may want to look into after market options which are(EDIT LOWER
Someone else can probably give you a better answer, but my short answer is YES