Just curious, why did you decide to go with the johnny joints?
The original rubber bushings were getting pretty worn out. The HPD30 was a swap from either a 93 or 94 Cherokee (per the guy that gave it too me), and I'm guessing the bushing was original, so they were "due" for something. I've had it for less than 2 years, I think it sat in the guys yard for at least a few years before it was given to me.
I'm not 100% sure, but after doing some bigger articulation that I had in the past a couple weeks ago, I think I felt what people describe as suspension binding. There could have been other circumstances (shocks maybe), but I felt there were a couple times that things weren't quite as flexy at the axle side of the suspension as I expected. I could be talking out of my butt (wouldn't be the first time) but I caught myself a couple times thinking "that sure doesn't feel quite right". Generally, I wasn't in a spot that I could hop out and crawl under, so I just kept going thru the trail.
Also after reading a bunch of old threads on here the other night, it seemed the discussion from folks who I believe know what they are talking about spoke to the benefits of having the Johnny Joints on the axle side, even for those people without JJ's on the frame side (like my RE Long Arms).
Lastly, I talked to MrBlaine the other day about what my plans were for "fixing up" my Front axle were, while this didn't come up specifically, I'd like to think he'd tell me if it wasn't a good idea for my rig. Even though I'm pretty sure I annoy him much of the time and I've been on an off his "ignore list" a couple times, I have no doubts he has a good handle for what works very well when it comes to these things.
I know some people would rather spend the money on replacement rubber bushings (potentially over and over) than spend more money on this JJ Kit, but I figured while I have the axle out of the rig and it's getting a "tune-up" that I'd go ahead and try to resolve one more potential issue.