The cable joins into the positive flat connector, it is held on by a small bolt you will see on the top of the connector with others. The main cable from the connector goes to starter solenoid.

You should be getting at least 13V, if not then it won't be the alternator to battery cable, when I tested mine there was around .10V difference from alt itself and at the end of the cable.

You do have a battery light on the dash working don't you?

Martin