I went through the same thing. Didn't look in the hole just stuck and allen wrench in there and stripped the first bolt. Had the M8 triple square wrench in my toolbox and the second one came out with no problem. I started drilling out the first one but never finished. Put in one strut and it is working fine.

Bought some parts from Germany and included that bolt on my list. I got it used for $5. Bought my struts from an eBay place in Miami. Sent me the wrong ones the first time and it took a month to get it right, but they did send me the correct ones the second time.

__________________
Doug

1987 300TD x 3
2005 E320CDI