I was attempting to setup a test network "WAN" link by connecting the CSU's between routers back to back. I never go this to work, but got practice assembling a cable and spent some quality time researching this. I was using junk I had gathered up and I didn't want to buy anything more just to do this. I believe I had the cable setup correctly, but I don't know if I had the right adapters to go from AUI to RJ45.
connecting routers/csu back to back. T1 Crossover cable.