I just bought a set of wrenches just to do the glow plugs ,one side has the open end while the other is closed with a ratcheting feature plus a swivel end ,made the job soooo much easier.Harbor freight for $20. and was well worth the cost.Its a 10mm for the glow plug while the small screw on the end is an 8mm which the wrench set did not have ,was able to find an 8mm wrench instead which worked great .Ive noticed while pulling mine that youll need to keep a long screw driver against the wire to release the peskey small nut of the end ,it wants to spin the wire with the bolt.A very important part about these small screws when tightening them back on is to NOT OVER TIGHTEN THE SCREW ,you will end up ruining the glow plug .It might be a good idea to just pull the whole injector lines while doing the job ,I get away with bending mine out of the way once the holding clamps are off but wouldnt recommend doing it this way.Im still having some cold startup issues ,mine I believe is due to a long needed valve adjustment which will be completed this week ,Ill chim in here to give a report on the starting behavior of the car after its performed ,could be linked to alot of mb diesel issues on the no start gremlin ,take lash readings on just how out the valves were before adjustment.