Does anyone know where to buy the tool used to tighten and torque this nut?

a pipe wrench has always worked for me

trying to use correct tools so I can torque the nut correctly...

Bruce Stone made some up for Boges. You can contact him here. Bilstein makes one for their insert. You can find them under VW Rabbit or Golf strut nut tools. They come in two sizes though. Do not remember which one is the correct one. The larger one I think is correct.

So you HAVE a "torque spec" for that nut?

That is typically a "Pipe wrench and two grunts" for me.

Even if you HAD the proper torque spec, how would you measure it? DO you have a 12" deep socket that can fit over the strut shaft?
Or a Giant crow's foot?
Some people overthink everything (I am usually one of those people :-)

I use these. (for lots of stuff)

I don't know that anyone makes a tool that will work with a torque wrench. If you really need a tool, you'll have to make it -- draw it up on the computer, do the math on how your 'crows foot' is going to change the torque setting, then have it laser cut.

Or just grab a pipe wrench or non-torque tightening tool, like pretty much everyone else.

I use a spanner wrench from a bike shop. I use blue lock tight and make it tight.

That special wrench above can be used to torque the nut to a known value with just a spring scale if you can find something accurate, but math needs to be done. Force(lbs)*moment arm(feet) AKA Ft-Lbs, but "two grunts and pipe wrench is probably sufficient.

Throw in an additional expletive just to be sure

I have that same wrench but it's dirty

found it... and it's a German car so yes it has a torque spec

thank you

The one Bruce made has 1/2" slot for torque wrench.

Ive used a coil over wrench before. Recently mine came loose and I tightened it up pretty easily with a pipe wrench and a rag.

I've tried to use those Bilstein collar tools.
If the torque required is more than 10 ft pounds you're more likely to end up in
ER than finish your strut install.

I believe every mechanic needs to get a feel for torque. Use a torque wrench for practice and use it on everything from small to large and get a feel for it if you need to. You may twist a small bolt apart, you may not get a big one tight enough on practice tries. But once you get a real feel for it, you don't need special tools and torque wrenches for everything.

I wouldn't use slip-joint pliers as a first choice.