Hi Dan,
The Aero-Commander built D model has a different aileron trim system than the earlier Meyers built planes. Meyers versions are indeed hydraulic while the Commander built versions use a spring system which is underneath the front seats.
The Commander version isn’t very effective and I know of several owners that just never bothered replacing the spring when it broke.
Also, if you email me at deansiracusa@gmail.com I’ll send you the latest version of the maintenance manual.