Zed Head

Now that would have been a good video.

The engine will run on three cylinders. Somebody actually cut one in half and ran it that way, if you recall way back. The Kent Moore Analyzer manual has more info that might help understanding. There might be a pdf file on the site but in the meantime there's this web site, broken down by single pages. - http://datsunforum.com/efi-troubleshooting-kent-moore-j25400-analyzer/

Some of the ECU's have all of the pins but many are not connected to anything. There's been a discussions about it. Chalked up to manufacturing "efficiencies" or overstock or things along those lines.

You might check the PCB circuits in the ECU that are connected to the sensors that control fuel enrichment. Coolant and air temperature sensors, for example. The AFM pins. If I had it sitting in front of me I might just check continuity from the PCB trace to the pin at the connector, for starters. Broken solder joints at the connector have been found and fixed, in past threads. If those are solid, then the components at the ends of the traces. Depends on how far you want to dig in to it. Could be fun. Finding that it starts lean. too lean to keep running, is a big clue.

Your work might save some future wiring harnesses if people follow it. If somebody had time, and a pile of fusible links, and a power source, they could probably define an approximate equivalent, fusible link to maxi-fuse. Just for fun. But if you don't need the excess amperage, it makes no sense to have a higher rating.

Are you going to take the shaft apart to get to oil seal #19? I got rid of my pile of 5 speed parts or I'd have done it already. Nobody has really dug in to that possibility as another source of the oil in the shifter cavity.

@zKars has the parts to be sacrificed, if he was interested. I think.

Looks like it might be a rivet. I'll bet you could grind the head off of it and the end would come off. Nissan never planned for this much disassembly, I'll bet, Might be some good stuff in the thread I found when I was looking for the picture. https://forums.nicoclub.com/transmission-stuck-in-first-gear-but-shifter-is-in-neutral-t602912.html

You're there...

There's a part with no number that looks like a screw. Maybe?

Actually that's a good find. Maybe that's the one that leaks, not #22. It would be #19 in the parts manual. There's an o-ring, and an oil seal. It looks like the end of the striker rod should come off, exposing that oil seal. Maybe you can disassemble it without removing the rod. http://www.carpartsmanual.com/datsun/Z-1969-1978/power-train/transmission-control/5-speed

Too far! I meant here, so we can see it.

What's the number?

That is a good point. The only reason to remove the rod would be to replace the o-ring. Were it mine, I'd dribble some oil down the shaft and see if the o-ring leaks. If not, it doesn't need replacing. Welcome to the site ZBLUE1.

Is that some sort of orthogonal hammer driver?