36*45 is standard I.S.. if it also says 41.8, or measures 41.8mm as the outside diameter, then it's an "in-betweener", a mix of I.S. and Campy fitment. Sweet, huh? It's a way some companies have been making bearings to install into Campy-fit frames, but to use I.S. crown race, compression ring, top cone...
So first, measure the diameter of the largest part of the hole in the head tube. If it's 41.0mm, then it's all IS. Get an IS headset or just the bearings.
If it's 41.8mm, the FRAME is campy-fit. If you're replacing the whole headset, just get a campy-fit headset, no problems. If you were hoping to just replace bearings in this situation, it may be more trouble than its worth.