You can reinforce the splines by cutting ~inch of outer spline from a junk shaft and welding it to the end of your good shaft. The ends are already tapered so you can butt them together and weld in place using the inner shaft as a fixture. Although it's still a PIA to keep the alignment straight. It took me several tries. I have extended both my shafts this way.
You also have to ditch the dust cover and replace it with a shock boot.
