You should have a field coil wire somewhere on there. It will come from the voltage regulator - the regulator varies the voltage to the field coil in the alternator, which in turn varies the voltage output of the alternator. You may also have a stator wire, which will also go to the regulator.
I've never seen an alternator that had an actual ground wire, but your description of it being heavy kind of points to that.
Alternators that are not internally regulated typically have 3 wire connections, with the case typically being the ground. The 3 wires will then be the positive battery terminal, the field connection (labeled "F"), and many times the stator connection (labeled "S"), which is a connection for the regulator to sample the voltage.
Last edited by PeteC : 02-02-2005 at 02:49 AM.