Bijan

I thought this was an improvement on the (non Porsche part) design, to limit movement of the strut brace bracket under the standard nuts that come with the brace . The holes on the end brackes were larger than the bolts, possibly allowing more than 1mm movement. I don't know if this is significant but from what I have read the brace is there to minimise minor strut tower movements.
The replacement nuts are steel metric manifold nuts, machined with a ridge as shown on the drawing, for a snug fit in the bracket holes.

David in LA

so where can you buy these and how much? thanks

Bijan

I bought the strut brace from a local Porsche Parts supplier, it is similar to say the Weltmeister. The manifold nuts were about $5 a pack of 4 from a car parts supplier. The machining was done by a local tail shaft balancing shop with a number of lathes, $15.