SteveJ

So, I have experimented a lot with different LED headlights. The current setup in my 260Z is H4 housings (the old Black Dragon H4s) with Auxito H4 9003 LED Headlights, https://www.amazon.com/gp/product/B07TQLK6SH. Those bulbs can be combined with about any H4 housings, such as Hella. They throw out a lot of useful light, especially on high beams. It's a reasonably economic solution, and the bulbs are polarity independent.

I had moved my brain down below the waist well before that since that was how I was doing most of my thinking back then...

I can pull the rear struts without touching the spindle pins. Detach the half shaft from the wheel & rear sway bar and you can swing the control arm down and out of the way. Of course, you'll need a good size lever to swing the arm down.

Chance favors the prepared.

If you don't know what you're doing, yes. The coil springs have a lot of stored energy, and typically you compress them to get the struts free, increasing the stored energy. If you aren't careful, they can come apart with great force. I had that happen to me once, but I avoided serious injury by having it hit me in the head. Seriously, the strut popped out of the spring compressor, and the spring struck me right at the eyebrow. It sliced me open, but fortunately that's a pretty stout area of the skull, so I escaped serious injury. Since it was on a military base, I got a free ride in an ambulance, too! Watch videos on changing out the struts. If you REALLY want to do them yourself, find a friend who is knowledgeable on the procedure supervise you. There is a trick to pull the front struts without breaking open the brake line, but it's not for the faint of heart. (Most instructions have you taking the soft line off the S-tube.) You'll have to take the brake lines off the rears to remove the struts. All this means that you'll be needing to bleed the brakes, too. This includes bleeding the master cylinder.

Rockauto The second link in your post was for a 280ZX. Those would not work on a 78. The price from Rockauto would be better than the other ebay link, plus there is a rebate available if you buy before 12/31.

Maybe a kit like this would work: https://www.amazon.com/dp/B087WNSDPV/

I believe I put some RTV on some shorter bolts and sealed the holes that way.

How long did it take you to clean the seats after feeling something furry there?

It ain't cheap, but it is available now: https://s30.world/product/01-77-till-12-78-datsun-280z-fairlady-z-fuel-tank-vapor

Here's one I purchased 5 years ago https://www.amazon.com/gp/product/B00PWNQMYI

Here's one way to check for leaks. Build a smoke machine. Start with the link below and work your way down the thread. I included a link to the YouTube video I used as a basis of design. Take off the valve cover. Rotate the engine so the intake valve on one of the front 3 cylinders is open. The cam lob for the intake valve will be down, and you can tell which are the intake valves because they line up with runners on the intake manifold. Remove the spark plug for that cylinder and plug in the smoke machine. Have someone push smoke through the cylinder while you're on the other side looking for leaks. If you have to do this solo, figure out how to set up your phone to take video of the manifold while you push smoke through. You may have to do this for each of the front three cylinders.

I chatted with him on the phone. I think he'll get it straight now.

I don't know if the C-Springs club ever formed, but there is the Z Car Club of Colorado. https://www.zccc.org/

And as far as "spoon feeding" goes, I've had to do more with people who had "engineer" titles. At least you found the source, and as you have learned the same lesson as many of us, it's frequently the last thing we f'd with.

I sent you my number in a PM a couple of weeks ago. Feel free to call to figure out how to get your wiring right.

There is neither a 400Z nor a Z35. It is a Nissan Z with a Z34 Series 2 chassis designation. Also the Z33 was 2003 MY to 2008. And the Nissan Z is 2023 MY.

We had a thread not too long ago about the 73 fuel gauge. Read through this for some ideas and watch the video of the bench test that is linked in the thread.

I don't know if this helps, but this is how it looks from behind the dash.

In Georgia, they think the signs identifying the freeway are the speed limits. If you think I-75 and I-85 are bad, you should try GA-400...

Actually it's not too important to find the exact place for the cross connection. The diode could be incorporated at the plug at the alternator. Of course, it might be easier just to replace the VR if it's bad, hence my suggestion of testing the resistance at the wires.

The problem is getting the connectors for the 280Z headlights. I could work around that in the 74-76, but even that involves backing pins out of the connectors between the dash harness and engine harness. See @Dave WM, even more reason to come up this way. There are even a couple of Publix around here for your wife.

What wattage headlights are you running? If the fuse was heating up enough to melt the solder (Yes, I've seen that happen.), a weaken connection would limit the amount of current that could flow. The good one might have partially failed, too, but not enough to take it out. You're also pushing more current through that circuit with the backfeeding of the other headlight. When you're doing the cleanup that @siteunseensuggested, don't forget to clean the contacts in the fuse box. And get off your duff and move up here so we can hang out.

Let's break things down. You said the car will shut off when you unplug the alternator. That means the alternator is backfeeding the ignition. That would be on the white/black wire attached to that plug. You may want to use an ohmmeter to measure the resistance between the white/black wire at the plug on the alternator and the black/white wire on the wiring harness. You'll need to backprobe the connector to get to the black/white wire. If the resistance is low, there is evidence of your problem. You will probably still need a diode to prevent the backfeed. Someone has definitely altered the wiring on your car. Nissan definitely NEVER used a wire nut on the Z wiring... (As an aside, I asked my wife if she could see what was wrong with the picture of the voltage regulator. She picked out the wire nut, too.) How long have you owned the car? It sounds like the IPO left you some surprises. What ignition system do you have on the car? I'm guessing it's not points. Anyway, you can wire the coil so that the tach doesn't work, and the car will run. Post some photos of the area around the ballast resistor and coil. If it's as I suspect, I have a video to help you sort that out. @Zed HeadThat was autocorrect on my phone. I'm back at my computer now, so improper words are my own ducking fault.

Let me guess...the car has an internally regulated alternator. It's backfeeding through the lamp wire to the ignition. MSA sells a plug that will take care of that.