Zed Head

Here's an example of the aftermarket parts. I'd just use the factory rubber. Better ride. https://www.rockauto.com/en/moreinfo.php?pk=6397113&cc=1209226&pt=7532&jsn=448

The factory bushing is rubber formed around a metal tube. Aftermarket PU replacements are a separate tube with two PU bushings. The factory part has metal teeth on the ends of the metal tube. Looks like the rubber might have left your bushing. The tube can be difficult to remove from the control arm. Big pliers or vise-grips might be necessary. https://www.tascaparts.com/oem-parts/nissan-bushing-rear-55555e4100

Uh oh. It looks like the clamping bracket has fallen off. You can see the threaded hole for the bolts. You'll need the bracket and the bolts. @Terrapin Z might have what you need. Parts 70, 46, and 47. Bracket, washer, bolt. Here's a few pictures from BaT. What should be there. Better check the front also, looks like it's loose or gone also, allowing the displacement. The diff mount crossmember does the job up there.

Leave the hose off and run the fuel pump by removing the starter solenoid wire and turning the key to Start. See if any liquid comes out of the nipple.

That sounds like a blown/cracked diaphragm in the FPR. Take the vacuum hose off of the FPR and see if it's wet with gas.

This is a not uncommon sign of a failing ignition module. Get ready...

It should mean that. The 78 TIU uses a plug so you should be able to just take a look and see if it's unplugged. If it's still there, I'd leave it just in case you need to go back to it. I'd also take a look at how the Energy-Pak is wired in, for future reference. It pays to be prepared with these old cars.

Be careful -

That must be one of the very earliest. There's nothing on the internet about that specific part number. Wouldn't be a surprise if it was starting to fail, like most old electronics systems do. Here's some general Jacobs stuff. I don't think the company lasted long. Looks like some of the kits came with a toggle switch to control a solenoid. Some sort of "high current" control. https://www.ebay.com/itm/168526052023?_skw=Jacobs+Energy+Pak https://static.summitracing.com/global/images/instructions/jac-forddis.pdf https://itstillruns.com/instructions-jacobs-electronics-energy-pak-7946376.html https://forum.ih8mud.com/threads/sanity-check-on-jacobs-ignition.1338701/

Just the coil or the complete unit? That looks like a pretty standard coil for electronic ignition. A little low on primary resistance for a 280Z ignition system but not terrible. https://www.summitracing.com/parts/JAC-380672T

@EuroDat might have some thoughts.

I installed my plug wires in backwards rotational order once and the engine started but ran like you-know-what. 1-5-3-6-2-4 counterclockwise is correct. It must have been running on two cylinders, I'd guess. I was surprised. 1-4-2-6-3-5

There are other possibilities. Maybe somebody overcleaned the case mating surface at the adapter plate. Maybe the countershaft drive gear isn't fully seated. Maybe the countershaft itself is not pulled back all the way by the nut. I don't know what stops the shaft when you tighten the nut. I didn't read through the assembly procedure to see how the various steps are checked. I've had some transmissions apart but have not rebuilt any. Just tossing some things out there to think about.

Any chance the bearing is not fully seated on the gear?

That might be because the wire is not seated fully in the cap.