These will have a ground connection on the back and NOT be grounded to the fender as all others.

The NSS grounds the solenoid in these cars - but every one I find is for manual transmissions.

Short of making insulating shouldered washers and getting really complex in mounting a solenoid and preventing it from being grounded to the fender - where are people getting their starter solenoids for Javelins with MOPAR automatics?

I would go looking boxes in the garage and find one, the wiring next to it maybe of help also it has both male and female connectors. They are a four wire connector one is not used. wire not in as good of shape as what you already have. PM me if you are interested in one or both.

Standard Motor products  SS 582   can be found on e bay

I ended up buying a "NORS" that was definitely correct - the application list included 72-73 AMC Javelin and enough other AMCs - and the photo they showed was correct (in fact looking at your pic now, it was like that one)

So one is on the way - from eBay, made in USA, etc.

Just for others and verification of part number:

NORS - part number?

The Borg Warner S113 and Standard Motor Products SS582 also look to be the same:

https://www.amazon.com/dp/B000C81T4Q/ref=psdc_15731411_t1_B000IURL4U

Your take.

Cross-checking with other sources is a good idea - but then that even fails. I have three cases of that failing - one was because TIMKEN's listing was WRONG for bearings, and another was because the national listing the auto parts stores, and Rockauto, use, was wrong for a MOPAR transmission seal.

The seal was for the shift select shaft - that small little seal that goes around the shift shaft on MOPAR transmissions. Should be simple, right? The listing from all of the parts stores EXCEPT NAPA, was wrong and you ended up with a large output shaft seal. O'Reilly, RockAuto, Advance, Autozone all had the wrong part number for that little seal. Only NAPA had it correct - likely because they produced the part themselves.

That's the most basic simplified explanation.

A stick didn't use an NSS like the automatics so had to have a self-grounding solenoid. Any car that used a NSS that broke the crank signal had to have a self-grounding solenoid.
For example, my 70 has the NSS at the shifter - so the solenoid for that car MUST be self-grounding and I could NOT use the solenoid for a 72-73 car on it, unless the solenoid was for a stick - I could buy a solenoid for a 1973 with a stick and use it on my 70

Well, it wasn't. I put the mounting bracket on the neg battery post and used a wire and touched the S terminal and nothing, so it was obviously supposed to say "not grounded" or something.
Of course the PO had really screwed up the wiring - the lt blue w/trace that was supposed to be the ground was actually connected in with the green wire that went to the S terminal. Good thing he didn't have the NSS connected! He'd have fried something. I had to put a longer wire on with a connector for the back lug.
I wish people who don't know any better wouldn't try to "fix" electrical issues - they almost always make them WORSE.

Anyway, I now have a proper starter setup - the NSS will now prevent cranking with the transmission in anything but N or P.

Not sure why there are multiple Standard numbers that look alike and have the same terminals, but I actually found another Standard number - if I can find it again.........

Standard SS590, SS582

NAPA ECH-ST83,

BW S113, 

AIRTEX IM1025, 

ESSEX 3235897 (AMC part number, made by Essex for AMC)