2000 GMC Jimmy

I am trying to drain and flush the radiator ..this is the first time for me on this vehicle where is the petcock? I see what looks like a drain just below the lower radiator hose but it has a white plug? in it ..is that it ..if so how would I turn in looks like it may need some special tool ...help

It may be it.
Is it made for a wrench or socket to go on it?
But sometimes a bear to get to or open up and get resealed.
You can flush it out threw a heater hose and sometimes it is easier to take the lower rad hose lose to drain.
Good luck

http://img406.imageshack.us/img406/169/0903071809bl4.jpg

I took a picture of it if that helps but loosening a hose doesnt sound like a bad idea I dont see how a socket would fit on there could be wrong though