[help] Undone mysterious plug on the gearbox...

[O_scar]

https://imgur.com/bqEgERT

Hello as you can see per the photos I've undone some random plug. My intentions were to do a gearbox fluid change, and I was meant to undo the filler plug. When I undid the mysterious plug, a lot of fluid drained everywhere (1-2 litres approx.). The fluid kind of smelled like burned clutch?? Just wondering if this fluid was gearbox oil or something else. I'm gonna replace the gearbox fluid anyway so just wondering if its any concern. 

As you can see I'm a very inexperienced 'mechanic' so sorry if this is a bit obvious or tedious to answer. Thanks

[Tony Prodigy]

The bolt with the question marks is actually the FILL hole for the manual gearbox. You did the 1st part right as this is always where you should start before undoing the drain bolt. I am concerned when you say that 1-2 litres of fluid came out though. It shouldn't have that much oil in there when undoing the FILL bolt.

The drain bolt is underneath at the very bottom of the casing. Same size bolt.

Have a read of this. It should help you.

https://practicalmechanic.com/2018/09/05/how-to-change-manual-transmission-fluid-toyota-corolla/