Hey all,
I'll grab a pic and tape measure this morning and post back. Apologies for the delay.
The factory service manual states 6 qts, "approximately."
In my experience this is pretty close, and depends on whether or not the tractor is level. Once it starts showing on the dipstick you only have about a half quart or so to go.
Factory Service Manual for early 2000 Series (aluminum rear)
https://drive.google.com/file/d/1NWT...w?usp=drivesdk
Factory Service Manual for later 2000 Series (cast iron rear)
https://drive.google.com/file/d/1frV...w?usp=drivesdk