Wiring an old dryer without a white ground wire?
The middle nut on the terminal board is the neutral. You can see the two white wires connected to it. You and also see the jumper going from the neutral to the housing. If you're going to go to a four prong plug, you will need a four wire cable and plug. The black and red wires from the new cable will go to the two outside nuts, the white wire will go to the middle nut and you want to remove the jumper. Then the green wire from the new cable will go to the screw in the housing, grounding it.