That's pretty common and often they have to be cut out using a Sawzall. The eccentric camber bolts are the same as the ones for the front. My recommendation is to stick with genuine Nissan bolts as they are made better than most of the aftermarkets. If you have any sort of lift, offset bushings are available on the aftermarket, but, if not, Nissan or aftermarket bushings will be fine. Compare the cost of R&R new bushings versus the price of a new control arm from Rockauto.
Refer this post for part numbers:
http://thenissanpath.com/viewtopic.php?t=11989