Could be the neutral safety switch in both cases. But Im not sure if the 510 had the a12 engine or L series. Anyway Im a z guy but datsuns share a lot of parts. yeah the neutral safety switch is on the tranny, has two wires on it. Looks just like the back up lamp switch. On z cars the NSS is the one on the rear half of tranny. It screws in, you can use an adjustable wrench. Cost would be low for new one. running over sticks can rip off wires. Let every know if this helps
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