There are ~10mm more threads in the trailing arms. I bough 10.9 grade bolts from Belmetric with a longer shank so the threaded section doesn’t extend out of the trailing arm just because. A bit more load on my bolts with coil overs and always better to not have threads at peak shear.

bingo.

Update: Jan 15

I purchased 2 new bolts from Porsche and the problem still persists. Without the shock, I can tighten the bolt down but with it, eventually the bolt "skips" and doesn't grab.

Here is the control arm, i've tried cleaning it out but the threads still look a bit ragged

http://forums.pelicanparts.com/uploa...1705380238.jpg

In your original picture the shock is not lined up with the trailing arm.
Try putting the bottom of the shock on first then jack up the hub to get the strut up into the top.
The angle of the shock bottom( alignment) is probably critical on your trailing arm.

Yep those threads look shot. You might be able to get away with a longer bolt but obviously it's a risk.

Best thing to do is to repair the threads.

Repairing these threads is a new experience for me, can I just use a tap to repair them? Do I have to remove the Trailing Arm or can I repair them in-situ?

To repair stripped threads you will need to install a Helicoil or Timesert.