Yep, you have SAI.

The sensor bung should be below the lower radiator hose.
Have a look.....

 

So... not to rehash this thing, but I don't seem to have a sensor on the radiator. Maybe the PO never installed a sensor and that's why I have the connector just hanging. And, could this be the reason for a P1117 SES code?

 

P0117 is for Temp Out Of Range Low, this could very likely be the case. Without being connected to anything, the ECU is seeing this as infinite resistance which would indicate low temp since resistance decreases as the temp rises. It's comparing the temp seen here to the temp at the coolant temp sensor in the manifold (and potentially other things) and the variance is causing the code. Your truck may have gotten a radiator out of (or for) a non-SAI truck. Or an SAI radiator that no one put a sensor in.