There is a single 10 mm holding in each Delphi module. Once removed, the entire assembly slides up and off of the spark plug. On the front most cylinder, the wiring harness has to be moved to allow removal of the module. Remove the cap on the wireway cover and there are 2 plastic fasteners holding it in place. These can be rotated and screwed down through the slot in the bottom of the wireway using a screw driver. The cover can be seen in the previous picture.