The clearances between the back of the alternator studs and the cylinder head are very close. In fact I think that there is a Pantera specific alternator because this is such a common occurance.
Get in there with a mirror and make sure that you aren't grounding the alternator terminal studs at the head.
If it's ok, start the car and put a voltmeter on the battery terminals of the car running and make sure of the voltage the battery is recieving.
Check the big chassis grounds under the trunk, etc.
Make an offering to Voltare, the god of the Pantera electrical system.
Something will give.
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