67 Cuda 273 - Extra Circuit for Amp, Seat Heaters

If you plan to do this, I'd go even further than what bohica posted

The top no1 problems in factory original wiring is:

Poor/ damaged/ corroded/ melted bulkhead connector terminals

Under fused, and fuse panel rust and corrosion

Undersized wire for ANY meaningful additions

The ammeter circuit is prone to problems ESPECIALLY when high current additions are added.

Ignition switch and it's connector

On my 67 when I got it there was a ONE VOLT DROP between the battery and the ignition. The switch, the connector, and the bulkhead connector were all culprits.

I'd perform the "ammeter bypass" and definately run large gauge wire from the battery (start relay stud) FUSED to power your new "stuff." And you DEFINATELY want a big alternator

Find out what all this $#&*#@#(% draws. "Heaters" use a HECK of a lot of power

This article:

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

Some ideas on converting ammeters to voltmeters

http://www.forabodiesonly.com/mopar/showthread.php?t=119480&highlight=ammeter+conversion