Ducati Diavel Workshop Manual page 710

Cylinder head assemblies: valves - rocker arms
Proceed in a similar manner to install the closing rocker arm (4) with the spring (19).
Load the springs (18) and (19) on the closing rocker arms (16) and (4) respectively using the tool 88713.2069.
Proceed to install the closing rocker arms (4) and (16), the springs (24) and (25), the relative pins on the exhaust side
in the same manner as described for the intake side.
Note
Always install the closing rocker arms on the exhaust side before those on the intake side.
Warning
Take care not to damage the shoe of the closing rocker arm with the intake spring during assembly.