here you go:
Magnetic drain plug for 6MT gearbox
the diff plug is much longer though, but i'm not sure how much clearance there is inside (or during operation). best to stick to a stock length plug. im going to change my tranny fluid soon. gears are crunchy when hot, stiff when cold.
It's been exactly a year since i changed the oil to Castrol VMX80, which i believe is a mineral fluid. Cheap stuff and silky smooth & light shifting so i dont mind doing it annually.