What size is the drain plug on the gearbox of tqs?

[fullpower]

just jacked the car was gonna change the gearbox oil until I noticed that filler plug is a bigger hex bit then I have , looked this up its a 17? But I've seen conflicting answers on the drain plug size/type?
And to top it all off I've noticed 4 dents under the car where the place that fitted my tyres missed all the jacking points ,muppets was perfect under there before.

 

[Bradderz_1988]

Its a security multispline socket im sure its an M16 i have one in my tool box at work i will double check tomorrow there about £10 for a laser one from halfrauds.

 

[Bradderz_1988]

17mm hex is correct for the filler.

 

[fullpower]

cheers,