Gridlock

I'm replacing my master cylinder. I've got the brake lines off and the mounting bolts off and go to remove it and there's still this metal pushrod thing. My question is how do I get the master cylinder off the pushrod so i can finish the job? Sorry if this is a dumb question

Ok so I got a 79 datsun 620 pickup. The rear lights consist of just 2 round brake lights. They work as brake lights and blinkers. In my jurisdiction I need running lights, brake lights, blinkers, reverse and license plate light. Front light section is fine but I really like to drive at night. Any clever/fun suggestions to fix this? I know electricity and have identified the rear wiring harness and stuff and can solder and have basic tools. Also this hot little muffin has less than 30,000 miles!