Most weird lighting problems in a Pantera are due to a loose ground somewhere. Each light socket is individually grounded and there is a central ground under the dash, more-or-less accessible if the console gauge panel is removed. Remove the nut on the stud, wire-brush everything and reassemble. Tighten'firmly' but do not snap the stud!
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.