Rear drive pinion nut tool
Moto Guzzi V700, V7 Special, Ambassador, 850 GT, 850 GT California, Eldorado, and 850 California Police models
Stephen Brenton's purpose made tool
Hole through center of 36 mm socket allows use with u-joint yoke. See Guzzi Manual, Fig 89. MG# 12356700 T1
Ralf Brinkmann's tool
I extracted this information from Ralf Brinkmann on the Yahoo! Loopframe_Guzzi news group.