Distributor drive gear shims
Moto Guzzi V700, V7 Special, Ambassador, 850 GT, 850 GT California, Eldorado, and 850 California Police models
Thanks to Craig Sheldrick for sending me some of this information in a private e-mail.
The original shims are 10 mm × 18 mm. 10 mm × 16 mm shims are easily sources and perfectly adequate. McMaster-Carr carries several thicknesses: