So I know this reply is maddeningly late, and I'm really thankful for everyone's replies. I ended up never finding the sensor but I think I know why: there's another connector that wasn't connected to anything but after doing a little research the unused connector is (what looks like) an exact match for a 2000 Ram battery temp sensor, and all the ambient air temp sensors I've gotten for this van have had the connector that I used for the battery temp sensor. This is the second time the van's thrown me for a loop like this because it uses the 2002 oxygen sensor connectors despite the 2001 registration. I'm beginning to wonder if this van is possessed or if the guys on the assembly line just had some weird spare parts lying around.

Again, I know it's months after the original post, but thank you again for all the help.