When my steering rack took a dump I also discovered my right from strut was blown and had leaked its oil. In for a penny already I decided I'd just pull the struts out and replace both inserts. After getting the assembly out from the passenger side I discovered the need for a 50mm wrench to remove the gland packing nut securing the insert (cartridge) inside the strut assembly. It's very thin, perhaps 3mm wide and designed to sit flush on top of the assembly tube. It was tight or perhaps partially seized and channel lock pliers would not open quite large enough to get a square grip on it.
So I ordered one of these through eBay:

Of course it didn't fit right either so I had to file out the inside edges to make it work. Here's what the OEM strut assembly looks like with the gland pack nut removed.

You've got to force out any remaining oil inside the assembly tube and pull the cartridge out, then drain the housing. The new KYB cartridges I ordered are supposed to be installed without any oil inside the assembly housing. Here's a pic of the new KYB cartridge installed fully into the assembly tube, and herein lies the problem.

Note how the new cartridge sticks out of the tube? Now compare that to the first pic with the OEM cartridge inside. I've been in touch directly with KYB to verify they sent the correct cartridges for the S12 and they confirmed part number 365031 is correct and then kicked my request to their technical department. I'm waiting for them to get back with me.
With the KYB 365031 here's how far the gland packing nut with washer goes by hand before bottoming out against the top of the cartridge.

Obviously this is not ideal as it leaves me dead in the water.