I don't know what a W3 is but I have a 530CK with Case-O-Matic (COM) Clutch. The Locations you describe are similar to mine. The Shifter on the Right is the HI/Low (Results in 8 Forward & 8 reverse) The dip stick is for the COM and your filling Plug is on the BELL housing up near the starter (fluid will migrate into clutch cavity). Hydraulic Fluid.
The COM control is the Lever on the Right side of the steering wheel. It must be UP to start moving (Converter Drive) and then you pull it down for Direct Drive. The lever will RE-Set to UP (converter Drive) every time the Clutch is depressed. The COM acts like an Automatic Transmission without GEAR Shifting. You change gears, clutch depressed, at Minimum RPM & then release clutch and Increase RPM to move
When selecting a gear
Manual 1-4 .
Range: low is UP , Neutral, and Hi is down, Shuttle: FWD, Neutral, Reverse
Hope This Helps,