you May need a brg & seal kit to install different gears into your carrier , everyone will have a different opinion of what is the best gear depending what you want the car for , personally I like taller gears , 2.7 or 2.9 for highway , 3.23 is good midrange gear , 3.55 are good for both highway & city depending on tire size , anything over 3.55 will limit highway use for sure