help on wiring ammeter on 1929 model AA

[cliff wheeler]

Just bought a 1929 Model AA 1 1/2 ton truck. Noticed the battery had been hooked up wrong and not using positive ground. Now I know why he could never get it running. Problem is the ammeter was melted and the wiring was all white wire...need to know which wires go to the back of the ammeter. Have a new ammeter to install but want the best way to test the hookup. New here and enjoy the site. Got the motor running and drives but need to rewire the tail lights and check out most all of the wiring. thanks for any reply. cliff