It's a Magneti Marelli SEN813.
Kiwi_Roy posted this in 2017 - The link is still good:
http://www.ebay.co.uk/itm/CRANKSHAFT-SENSOR-ALFA-ROMEO-145-146-1-4-FIAT-Tempra-Tipo-1-8-LANCIA-/251703577340?
This is the exact same part mine arrived quickly direct fit £24.96 as opposed to over £130 from Guzzi I had to really look hard for it I have told the seller and he is going to add the Bike OR SEN-813 to make it easier to find this sensor is fitted to a whole load of Guzzis V11 series and all these
Fits Moto Guzzi Quota 1100, V11 Sport ALL, 1100 Sport IE, 1100 Sport Corsa, Bellagio, Breva ALL, Bellagio, Cali EV, Cali Jackal, Cali Stone, Cali Special, Cali Vintage, Centauro, Daytona RS, Griso ALL, MGS-01, 1200 Sport ALL, Norge ALL, Stelvio, V7 Classic, V7 Cafe, V7 Racer, V7 Stone, V7 Special, Nevada 750 (2004-2013) http://www.gutsibits.co.uk/pr/img/HelpIcon.gif
Phase Sensor