Vintage Cars: W115 head bolt size, bolt size, thomas hanson

Question
I have a W115 where I need a headbolt Mercedez in South Africa cannot locate the part for me after I left the original bolt with them. The size they want to give me is 12mm and the bolt I need is smaller any help on locating it or can I some how find the part number. I even provided them with the engine and Vin number

Answer
well the best bet is MBCA classic center or email thomas.hanson@mbusa.com  at the center with your specific question. he is the part manager.  Make sure you have your VIN , they should be able to help

If not, join the www.peachparts.com   Mercedes Forum and post, the guys there will be able to assist