Explain the 300 dollar shock to me, What the... Options

[emerygt350]

An insert for 275? What and why? Is it just rarity? Some strange one off design that no other car uses?

[mepstein]

If the struts have been switched out, you need to figure out if they are Boge, Bilstein or Koni and if the caliper spacing is 3” or 3 1/2. Early 3” Boge 911 struts will take the same Boge inserts as a 914 but everything else is different.
The most practical way to tell if the torsion bars are bigger is to measure them. If they are 911/914-6 size, they are 1mm larger. That makes them stiffer but doesn’t automatically make them “harsh”.
So the first step is to figure out what you have so you can decide on the best solution.

[chmillman]

If the struts have been switched out, you need to figure out if they are Boge, Bilstein or Koni and if the caliper spacing is 3” or 3 1/2. Early 3” Boge 911 struts will take the same Boge inserts as a 914 but everything else is different.
The most practical way to tell if the torsion bars are bigger is to measure them. If they are 911/914-6 size, they are 1mm larger. That makes them stiffer but doesn’t automatically make them “harsh”.
So the first step is to figure out what you have so you can decide on the best solution.

So, the bolt center to center spacing on the calipers looks to be around 76mm or 3", so older non-S 911 parts I assume.



Viewed from the front they look like this:



The green dust cap up top looks newer than the strut itself...

And I did actually find a marking on the rear springs...





Did a search for the number but didn't find anything right away, but I assume SP100 indicates 100# springs? (more or less stock... hopefully not 100Kg...) 912 parts?
Edit: AI is telling me they are probably aftermarket from Weltmeister.

The sway bars are 15 front / 16 rear (stock option size)