Where is the Camshaft position sensor located?

I'm wondering if maybe my truck had the engine replaced before. I bought it with one from a different vehicle because when I removed the camshaft sensor at the back of the block next to the oil sending unit, it looked completely different than all the YouTube tutorials I have watched. The replacement part from AutoZone doesn't even fit or line up to bolt in. Nor do they have one that even looks the same as the one I pulled out.