Can't imagine the bushings you used had anything to do with your failure. Those bushings are designed to allow rotation type movement whereas the stock bushings are clamped solidly in place and movement is by torsionally twisting the rubber inside the steel bushing cup.
How did you remove your old bushings? Did you use heat in your removal process? If so, you could have used too much and caused metallurgical damage to the arms since the picture shows the failure appears to be at the weld.
Just a thought.
I bought some new OEM style upper arms for my '03 and cut the bushings out and installed Super Pro bushings, so I didn't use any heat.
So far so good, but I don't off road.