[Volhv]

The aft bolt is a standard m8 x 55.
The one that you still have is a m10 x 1,25 x 50, but from the picture, the threads look to be mangled.

As far as the tensioning strut goes, check to see if it's the RH, or LH threaded rod end that broke. You should be able to find a metric rod end (hardware store) if it's the one with the RH thread. Buying a whole OEM rod is not cheap. Even used. At least I couldn't find one when I needed one. Mind you, in Western Canada we don't have 944's at auto wreckers.