As more and more S-chassis gain power, some of you have succumb to upgrading your axles due to failures.
Not only the increase in power, but also the lowered ride of the car puts additional stress on the axles themselves.
Let's first take a look at the type of axles that come with your 240sx, which are the Tripod style joint.  There are 3 points of contact which transfers the engine power to the shaft at changing angles and axial movement to the wheel.  As the axial movement increases, it puts additional stress where the bearings ride on the inside of the housing, weakening the joint, and possibly leading to failure.

Imagine the angle and stress on your stock axles!

The 350Z axles are Rzeppa or ball in cage design.
This design is used more commonly on cars with higher performance due to 6 points of contact instead of 3.

The ball in cage is smooth and it's design is to reduce the angular contact as in the Tripod design.
The ball bearings glide along a set of grooves inside the housing allowing the torque to be transferred more evenly.  

Compared to the tripod design, the ball in cage distributes the load much more evenly preventing premature failure.

Our axle adapters are designed to be welded onto the stock 240sx output shafts.
First the flange on the output shafts need to be removed.

At this point, you will need to machine the output shaft down to fit inside the adapters.  This is where depending on your setup, you might want to take some measurements to see how much to machine down.

Done on the lathe to ensure accuracy.
Make sure to test fit.

Nice and tight.  

You can see below what the 240sx output shafts look like with the new adapters before being welded.

Below is how it looks all zapped up.

These are mild steel, so getting painted or powder coated is highly recommended.

Painted and final test fitment on the 350Z axles before getting installed on our car.