Could someone tell me what exactly a spline does and what the difference between a stock 28 spline and a 31 spline upgrade. I am putting in 4.10's and am considering the spline upgrade after a few suggestions.
Thanks

 

The reason for upgrading is becuase with the higher number of splines on the axle (grooves on the end that slide into the posi) the stronger it is because it has more splines holding it in the posi. So 31 spline smeans there are 3 more splines helping hold the axle in the posi unit. This and the fact that aftermarket axles are made with better materials and the way they are heat treated etc.. makes them alot stronger then stock axles.

If you plan to drag race with sticky tires this is a must do upgrade. And by sticky tires i mean drag radials and stickier.

 

splines are liittle wedge shape grooves in a male/female joint. If you look at the edge of a quarter you'll see a small version of what they look like. Imagine a whole roll of quarters with all the liittle wedges lined up and you have the basics of it. They increase surface area and provide a mechanical lock. More splines generally means a larger axle shaft and more strength. 28 is fine for most street applications. 31 is a good idea if you're fixin'a beat on your rear end with hard launches.

If you have the money and your doing gears anyway, now's a good time to do it if there ever was one.