Hi,
Welcome to the forum. For the 6 bolts I would suggest your local Mercedes Dealer, you will get the right size,probably pre-loctited and they fit like they should do, especially in a critical area like bolting up the half shafts.
Last bolts I bought were for the brake pad retainers on my Sprinter, and they were not that expensive. If you do not have a local dealer then try some of the dealers that sell on Ebay, I have had parts from MB Newcastle with no problems. If you add where you live, someone might chirp up with somewhere helpful.
Steve