radiator drain plug?

[quagmire]

hi, went out to drain my rad yesterday expecting to find the rad drain plug easy to locate, after getting the sump guard off and finding another radiator underneath (air con?) i found a black wingnut style plug about 1 inch wide.

does this sound right?

i couldnt see the bottom of the bottom hose and didnt wanna just open it in case it was the wrong one (and it was starting to get dark)

any help much appreciated.

[BUSHWHACKER]

Yup, that's the one.
Bottom of rad, passenger side facing engine.

[quagmire]

lovely.
ta very much.