'95 Geo Prizm Control arm bushing--Front and Rear

My prism has 145K miles on it. I took it in for brake pulsations and was told that the bushings on the control arm were worn out. It took 6 days to find the parts–they were unable to find rear bushings, but they did find front bushings. I went on the web myself to locate the part(s). I found listings for only one type of bushing for a 95 geo prizm. No differentiation between front and rear. The mechanics at the shop told me that there WAS a difference and it was impossible to find the rear bushings. What is going on here?