Call your local Toro dealership and speak with the service department. They should be able to tell you if there is a timing procedure.
This is for the Procore 864:
"Coring Crankshaft Timing
On the ProCore 864 aerator, each pair of crankarms
joined through a bearing housing are assembled with
the crankarm journals positioned 180o apart. The coupler
assemblies that connect these pairs of crankarms
allow for proper phasing of the crankshaft to allow minimal
operating vibration.
NOTE: On the ProCore 864, the numbers cast into the
crankarms will not align with the raised indicator marks
on the bearing housings."
https://media.toro.com/servicemanuals/07155sl.pdf