Hi all. I’m hoping someone is able to tell me which glow plug I need for a 2010 cls 350 CDI. It has the OM642 3L turbo V6 Diesel engine the problem is that this engine uses 3 types of glow plug. The 4.5v, 7v or a ceramic. Would I be correct in assuming that different control units would be required for the 4.5v / 7v and how would I be able to identify which one I have ?