cnano423

Hey guys im in the process of gathering parts for my '12 silverado 2500hd turbo build (GT45). I see most people use the oil block off plate above the oil filter on the driver side of the engine. I noticed that I have lines in mine running to the oil cooler out front that I did not expect to see. There is a plug on the side (im assuming to hook up a oil pressure gauge for diagnostics) and I would like to T off there with a 4AN fitting to feed. The red arrow in the pic is pointing to this plug. My question is does anyone know what size/tread/pitch that plug is. Thanks is advance.