Axle studs-stock length or 3"

The 3" studs are usually for racing.

But, most modern style aluminum rims have a much thicker cross section at the hub than even older aluminum rims, so stock length lugs sometimes come up short, even if you're just taking about a driver. Some folks also run spacers to adjust the fit of aftermarket rims, so if you're doing that you may need some more length as well.

If you're just running stock steelies, there's really no need for them, and they'll stick way out and look funny.