Scotty,

What you're referring to is the coolant temp sensor (the adapter/extension is a 3 pin). #346 is an 8 pin (2 x 4).

It was a good guess, I went and checked after I saw your post.

It's ECM (ignition coils), ?????, a ground (to ECM stud), cam position (knock) sensor, and a second coolant temp sensor.