Example of Old Style Housing to fit this VK1051 - Read on
BLACK ONLY - 4cyl Cap and Rotor Combination (This Cap is Notched to accept the locating tab on older 123ignitions) Because of tooling differences you may need to pass a file along the metal edge of the 123 for proper fit. About 1/2 mm needs to be removed.
All newer 123Ignitions with side access to the switch or USB connection have an adjustable tab on the side of the housing to enable them to accept either the Tabbed VK 106 Beru cap or the Notched VK 105 cap.
If you have an older style 123ignition and would like to fit an angled cap or a tabbed cap like the VK106 you will need to notch the housing. It can easily be done with a Dremmel tool and a cutting wheel.