All Quads Modeled Gears with (6) Teeth Styles and (6) Center styles that be interchanged to make 36 combination
But there are more options than those 36. Using the 3ds Max 2010 File you have the ability to change the thickness along with inner and outer radius
I included 17 additional different combination by changing the radius and thickness for those who don’t have max 2010
Exported obj files included
So with the 36 Main gear options plus the 17 addition combination I already prepared that is Over 50 Different Gear styles.