Hi Sean, Paul, and Andy, just rebuilding one of these engines. It is difficult enough to identify the crank mark with the engine out, never mind in situ. One of the gaps on the " chopper" for the sensor is slightly deeper and has squarer corners than all others. When correctly aligned a quarter drive socket , 7 mm I think, dropped in a good 4 mm further when slid down the locating tube for the crank sensor. The correct tool is probably marked for depth. I noticed that the chain has three marked links, one for each camshaft, and one for the pump. Also both cams have holes for locating dowels, as does the pump. I aligned the pump anyway, but did not see the necessity, as it is common rail high pressure. I also set it up and confirmed timing with the rocker shafts out, so no danger of contact, easy to say as engine stripped anyway. Cheers, Tom