I have a 89' John deere 550g that is leaking hydraulic fluid from the rear panel. This is the panel that covers the transfer case. Also located under the hydraulic tank and fuel tank. Just noticed this after digging up a stump.
This rear panel covers the transmission. This machine has a 4 speed powershift transmission in it. You can remove that panel pretty easy but be sure and drain the sump. There is a pipe thread plug on the under side of this compartment that will take a 1/2" ratchet. Have several drain pans ready, its about 30 gals if I remember right.