Ralph,
This statement might not apply to your '58 Apache, but on an AD ammeter, the charging system and all the loads (almost all) connect on a post that is physically behind the 'discharge' logo on the front of the gauge. The large wire going to the battery connects on the post located behind the 'charge' or + notation on the gauge.
Even if you had your gauge hooked up bass-akwards, the needle would still deflect, just incorrectly.
Stuart
