If the RC X-flex control arms are the type with the threaded washer on one side that retains the bushing, I would not trust those. I had upper rear X-flex control arms on my previous X, which I sold to a friend. After one off-roading trip to Colorado, he kept telling me about a clunking sound from the right rear. We took it to a suspension shop for a diagnosis, and it turned out the threaded washer had come out. Not threaded out, pushed out past the threads, and pretty much destroyed the bushing. We checked the other side later, and it had begun to do the same thing, but had not progressed to the point of coming completely out. My buddy went back to oem control arms.
I have to give credit to RC, though, when I told them what had happened, they sent me two new control arm ends at no cost, which have been redesigned to use a snap ring instead of the threaded washer. Much better design. They're still in the box in storage, though...
If you check out the arms you have, they turn out to be RC, find they have that old type of end, and you want to keep the arms, I would contact RC and see if they would upgrade your arm ends. Doesn't hurt to ask.
