You said " I measured the power coming off of the truck and I am getting about 14.5V at the battery terminals with the truck running. So it seems that I have good batteries and good power coming from the truck."
If this was measured with no batteries or other load connected,it does not necessarily mean you have a good connection. With no current flow through the wires any voltage drop due to excessive resistance or bad connection would not be evident. You should remeasure with some electrical load on the connection.