Yeah I linked the wrong one, my bad. I just noticed there were a few versions of the kit.
Here's what's strange: I bought a front shaft from another XJ to run in the rear (one of the perks of the XJ platform) and rebuilt that shaft with the same non-grease-able kit from denny's in 09 but it's now on my work bench with dried up needle bearings. I could blame my salt-belt region for that but I would've expect it to last a bit longer. I have an Adam's Driveshaft back there now and rebuilding this shaft to run in the front again.
Seven years is a decent length of time but when I think of it, my 99 TJ is still on it's factory front and rear u-joints.