Sorry, shoulda read your question more closely before firing off my answer Rick!
I see you mean the oil cooler lines….Duhhh
Not sure about the threads in radiator , but the lines are 5/16” inverted flare
The radiator takes a 1/2 tube nut that is 3/4 -18.......I bought the nut and plan on pluming it and welding it shut. I could not find a plug but one must be out there. This is for a stock radiator.