the dash regulator is probably burnt out, it turns 12 volt into 8? for the gauges. might be 5 volt cant remember.
Its marked what it is on the HZ drawing Id post that but I gave that book away years ago
yea they have a 5v reg for the gauges, when it fails it pumps out full volts to the gauges and if they are at a lower ohms it frys them, they can be rewound and calibrated and elec reg fitted so it dosnt happen again