I installed jba UCA's on my 2004 4Runner - finally decided to set correct caster after over 15 years of driving with 4 deg off with no issues.
When I got the UCA's, I noticed that the boots are not tight on the bolts and there is an aluminum bushing between the knuckle and the boot. I called jab and asked about this unconventional "solution", and they assured me that everything was fine and as intended. I assumed that for that kind of money, they would do it right. WRONG!
In less than a year, the ball joints have failed (yes, I lubed living hell out of them every time I did an oil change) because the boot was loose, and water/sand got inside and ruined the joint. It was not an accident - it was a case of lousy design and/or implementation.
Needless to say, their warranty doesn't cover ball joints...
I was told that chevy silverado joints have the same configuration without jba's defect. As much as I hate putting anything chevy on my Toyota, I have no choice.
BUYER BE WARE!!!