Easiest way is to find an old axle with the right spline and cut off each end.Slip one end into a bit of pipe and weld it .Drill a hole in the other end of the pipe and weld a nut over the hole. You can then screw a bolt into the nut so you have a pinch bolt arrangement. Slide second piece of axle into the pipe and lock in place with the pinch bolt.

Fit your adjustable axle to the car. When the car is on the limit strap and axle is at around 22 degrees you need to have some end float in the axle.

When the suspension is compressed to a point axle is parallel to ground you have to make sure you still have end float and axle is not hard up against CV flange and hub centre cap.