Zed Head

The GMB design with the stamped steel impeller is not the desirable one. Generally, people feel that the cast impeller design works better. There are several of those on the site.

My 1976 switch and light worked fine, many times, as I tried to bleed my front brakes in the days after I got my car. Turned out the calipers were on the wrong sides, upside down, and there were big bubbles in both. If I recall correctly, pumping the pedal would cause the light to go out and the front brakes to work. The workout probably added many miles and years to its life.

I left two of the same image in the post as an act of rebellion against the wonky post editing software. But, yes, those are the springs I thought I saw. Maybe the switch tended to get stuck and that's why redesigned it. There's not much to it, no reason to redesign unless there was a problem. Functions are identical.

GMB pumps are available on Rockauto right now. Looks the same as yours.

I see the logic now. They might have added a self-centering mechanism that didn't require a pressure differential in the later revision. Maybe the ramped portion of the valve plunger. Still unclear to me though that the original 72 switch, in good shape, required a reset. Just haven't seen the firm example. Even your anecdote is about broken switches but nothing about resetting a stuck one. If I had one, I'd test it and see what happens. If you can reset it with a small screwdriver you should be able to get it stuck with one. Not really arguing just looking for some solid evidence. Here's the 72 and 76 switches, you can see the ramped area in the 76. It looks like the 72 has a spring to reposition the valve, but it's not clear. The 76 switch might even work in a 72 but then you'd have to wonder about the VIN. Just kidding.

Take some better pictures of the spot. Looks like one of the stamped steel impeller pumps. Nobody really likes them.

Laws are determined by the state, sometimes the county. By people. That's how laws work, they're just written rules, written by people, in this case, for the purpose of assigning ownership. As already mentioned, there are many different laws in the USA. We are not homogeneous. Morality is determined by intent. Intent has not been determined here yet. If the "law" says that you can leave an old VIN ID on a part used on a separate car with its own VIN, then both of your cases are incorrect. The law will have been followed and whoever did it had no apparent intent to "steal" from another person. All they need to do is follow the law. The OP has moved on, apparently, and may or may not be hiding the car for ten years. If he is hiding it then maybe he is committing an amoral act. But, he probably hasn't really though about it, so god might give him a pass. Really though, you're kind of going over the top here. It's still just a car with some numbers attached, and no documents showing which are correct. Bringing the concept of a supreme power in to the discussion is a bit much, and nobody has advocated breaking the law. We're just describing how things are over here in the wild west. This is not England. But, since it's a topic, are the laws in all fo the territories of the UK identical, or are there differences? Might be a good point of reference for you. The OP bought an undefined legal problem and may or may not try to resolve it. Found my example on Wikipedia. We're not so different. https://en.wikipedia.org/wiki/Law_of_the_United_Kingdom

We need to know more about this "bolt buster" induction heater. Is it 120 or 240 volt? Where can you get them?

It doesn't stay there. That's my point. There's nothing holding it there, by design. If you fix the problem and restore the proper pressure to the other side of the switch, the switch moves back to its proper centered position. Like Nissan says.

It might be that the early switches just got gummed up and stuck. But it doesn't seem to be a factory described reset procedure. Short version...

I'm not an expert n the area, just regurgitating knowledge I've consumed, and adding some basics to it. The cam lobe is the area that almost always has wear problems, not the lash pads. Wait a while and you'll probably get some more experienced views. Doesn't seem like you have a major problem though, just minor details to correct.

I think that this might be an urban legend. Maybe country too. Just saying, the later FSM's say otherwise and I had the issue on my 76 and it reset just fine. On top of that, add that it doesn't really make sense to have to reset the switch, since it moves by pressure differential, and it would be surprising if they didn't include this piece of knowledge in the FSM, since they talk about all of the other details. I haven't seen a case where anybody actually had to reset the switch. I think that the light just goes out when you fix the pressure differential. And, to keep piling on, the FSM does say explicitly that the switch should not be disassembled, but replaced. Beside that, I don't see that the brake light is staying on in this case, which is the real clue. You can also check continuity at the switch itself if you're not sure about the wiring. Anyway, just one of those things that bug me. Carry on.

@Matthew Abate lives in New Jersey.

A plausible story might be that the PO installed a set of rebuilt rocker arms, didn't inspect them closely, and missed #8. Or got in a bind and decided to use it anyway. And didn't properly tighten the bolts. I can't see how you get a groove like that on #8 except during regrinding of the pad surface. If the cam lobe had worn out there might be a groove closer to the end, but not where that one is. If the others are all good you'd probably be okay just replacing the bad parts.

I thought that the "hard pedal" or abrupt brake actuation was almost always the reaction disc in the brake booster. I've seen people talk about resetting those switches but I think that the FSM describes that they automatically recenter when the pressure differential problem is removed. In the later FSM's anyway. They don't mention any need to replace it in 1972. Some people think that they divert pressure to the working half of the system but I don't think so. The master cylinder's serial piston setup will still pressurize just with more travel, I think. But if you have a hard high pedal that would mean both front and back are getting pressure. p.s. I think that you're blending up your terms and words. There's a switch, which you show, and distribution fitting (3 way connector), and a proportioning valve.

I meant that the OP should show the back of his. I've never seen one of yours on an AFM. I think it might be a hardware store replacement. I think that the rubber corks are stock, although many AFM's are sealed with clear hard sealant. Who knows.

That's a good one. Show the back of the piece. Is there a hole that fits over a nut or stud? The AFM plug is solid.

Looks like the rubber plug for the AFM's idle air bypass adjustment screw hole. On the lower right corner of the side of the AFM, by the black cover. Tends to pop out and fly away when removing.

Are you going to see if you can split the two parts of bad 3rd gear apart? I'd like to see how they're put together. Could be that whatever caused your 3rd gear to start coming part also bent it a bit. Maybe bent the shaft a bit also. I hit a curb in a four wheel drive Pathfinder hard enough to bend the bearing cage around the outer front wheel bearings. Took me forever to figure out why the front wheel would whine after driving some curvy roads. I replaced only the inner race and bearings, in the old outer race and got another 100,000 out of it with no noise. My point is that big chunky metal pieces will bend if you put enough force on them It's surprising.

Which set of parts did you end up with? You had a clicking noise and reinstalled some old parts to see if it would go away. Just curious, to fill out the story. Once you get off of that sand bar you might wish you had the 3.9 diff installed. It wouldn't be a huge difference, just a little less finesse required when starting from a stop on a hill, and a bit less wear on the clutch. I noticed it, here in the hills of the Portland metro area.

The story behind the two VINs makes the car more interesting, to me anyway. I'd try to flesh that out. Ten years from now it will be even more like a pile of parts, instead of an interesting car. An old all-original one-owner well-documented 240Z is neat, but there's really not much excitement to it. Not a whole lot to chew on, mentally. I'd spend more time at the car with a story, at the car show, than at the all-original car. But that's just me, one of many different types of aficionado. The basic question here, is what really makes a car a car? The point of my rhetorical question. Which has many answers, depending on which type you are.

You're welkome.

Nissan called it a shim.

You got clips. They're on the outside of the backing plate. They slide off. They tend to get dirty and stuck. Good luck.

Considering how many parts can get replaced during a restoration, it seems kind of limiting to make a small piece of firewall metal so important. If a person cuts that rectangle of metal out of a car and installs it in another car, which car is the legitimate one?