It's hard to believe that a vehicle designed as well as the JK Wrangler would come from the factory with such a glaring weakness. That weakness is the JK Rubicon Dana 44 frontend. The housing is weak, so the aftermarket has stepped up and offers beef-up kits to address that. The axle shafts look strong and sport a beefy 1550 U-joint, but those have a problem, too.
The OE half-moon C-clips work out of their retaining groove, falling out. The 1550's cap then works its way out and falls off, too. Now, the joint rattles around in the yoke ear until it binds and breaks the ear. We machine the OE axle so a full-circle clip can be used, but, while this works better because the clip ring stays put, we weaken the axle by machining it.
The crew at RCV Performance Products are building JK Rubicon Dana 44 CV axle shafts that are as strong as 35-spline Dana 60 axles. Manufactured here in the U.S.A. from aircraft-quality steel, the axles are one of the best upgrades you can do to your JK.
A U-joint will speed up, slow down, and experience knuckle bind when turning at full lock (you know the feeling), while the CV joint doesn't do this (constant velocity - get it?) and is smooth as glass. Turning radius isn't compromised. There are no yoke ears to break so that's now a non-issue. Minimal maintenace is required - just shoot grease into the CV via the conveneint zerk when servicing the JK. RCV supplies a high-durometer urethane boot that protects against water, mud, and other debris. The axles come with RCV's "You break it, we replace it" no-questions-asked warranty.
RCV builds these not only for the JK Rubicon Dana 44, but for CJ, YJ, TJ, and JK Dana 30 frontends, too. They also offer them for many other vehicles, even hybrid applications.
I'm going to use these on the JK and will report on longevity. The RCV Performance JK CV axles are the bee's knees.