Let's see <pulls out crystal ball and starts polishing it> hmmm - nothing definitive there...
Really - you're asking us to guess.
1) Incorrect installation
2) Poor quality parts
3) Unknown contamination
By the way - telling us you have 235s on it tells us absolutely nothing - 235 is a tread width, you need two other dimensions for it to make sense.
I have 235s on my GV - OEM on that GV is a 235/60R16, but what I have on are 235/70R16, and those are almost two inches larger that OEM - get the idea?
I have one question for you - you noticed slop on the right front wheel, so you tightened the wheel bearings and then checked to see what was moving - am I getting the picture right? That's kind of pointing to suggestion #1 - the wheel bearings on a Samurai have a particular sequence in which they are adjusted, you don't just tighten them until the play is gone (as you do with some vehicles), and similarly, the king pin bearings have a specific adjustment procedure where you need a scale and shims to set the preload correctly.
Serious question this time - were you aware of the correct procedures and were they followed. You don't need to answer me, the answer doesn't make a difference to me, it might to you - it'll just move the cause of the failure to suggestion 2 or 3 - both of which are equally serious, I've had a set of ball joints (on a different vehicle) fail in less than three years, yes it was a 4WD, no it was not used off road during that period, and those were sealed with a rubber boot, like most ball joints have, which was intact so no contamination.
