i cannot get brake fluid to rear brakes..lines are clear,,is there a a shutoff valve in the block where your master cyl lines meet up with the front and rear brake lines with the electrial connection on top?

Did you replace the master cylinder? If so, bench bleed it again and reinstall. Open one of the rear bleeders on the rear wheels and leave it open until you see fluid leaking from the bleeder. Gravity should allow fluid to flow to the rear lines. Also, check the rear flex line above the "pumpkin". There's always the possibility that it may have collapsed internally. Once the fluid begins to flow, you can bleed the brakes normally. I assume that the front brakes bled normally?

You could havd a blockage anywhere in the rear system. Start disconnecting things in the back and work your way forward till you get fluid. I agree that a good guess is that the rear flex hose is clogged/collapsed.

hose collapsed