Bleeding brakes

V8 Four Wheel Drive Automatic

I just rebuilt my back brakes, drums, shoes and wheel cylinders. The back brakes were not working, and the shoes and drums were wore out, drivers side wheel cylinder was leaking.
So after I replaced everything, I went to bleed the brakes, but I got nothing to come out of bleeder valves, no air, no fluid. Starting at the master cylinder, I loosened the line connections, one at a time to check for fluid. I Had fluid at all connections in the engine compartment. I followed the line down the frame to a rubber line that goes to center of rear axle. I could not get that connection loose. Could that rubber line be clogged or something. What else could stop the fluid from getting to rear cylinders? Thank you for time.