https://www.partstree.com/models/ch20-64507-kohler-command-pro-twin-engine-basic-version-20hp-14-9kw/02-crankcase-1/
Kohler CH20-64507 - Kohler Command PRO Twin Engine, Basic Version, 20hp, 14.9kW 02 CrankCase Parts...
02 CrankCase diagram and repair parts lookup for Kohler CH20-64507 - Kohler Command PRO Twin Engine, Basic Version, 20hp, 14.9kW