Don't know for sure. I think some have a drain plug in the bottom. The one picture in the .pdf file shows a bleeder/drain plug on top behind the reservoir. That will be something else you'll need to know if you change the fluid and/or filter. What the procedure is for bleeding the air out of the system to get it to work right.
Here's a thread I found over at MTF which I think would also apply to your model:
- replace drain plug
- fill with 0.7L (1.5 pt) of SAE 90 into upper fill plug (front of diff)
- oil should be a short distance below the fill hole
- replace fill plug
- clean off transmission to prevent contamination (requires removal of fender deck and fuel tank, etc.)
- drain (I assume there's a drain plug on the bottom)
- remove vent plug beside reservoir
- add new oil (SAE 30) until oil appears at vent
- rotate input & output shafts to release trapped air
- add more oil until oil reappears at vent
- reinstall vent plug
- fill to 140mm below reservoir top (full mark).
I've never personally owned or worked on a 100 series Deere myself. My LT150 is a totally different setup with a Tuff Torq K46.
(I wish I had your much more robust tranny on it. )
I have read posts where people actually remove and turn their transmission upside down to drain the oil through the vent and fill port. I hope that's not the case with your machine . This would seem extreme but, so is ruining the hydro from lack of maintenance.