amp gauge???

i am having wiring issues i had a ballest resister go out and a fuseable link go out as well i fixed these problems and now when the car cranks and is idling the amp gauge slowly starts to climb it is a 73 duster and the gauge ranges from -40 to +40 it goes a little under half when i turn the key to the on switch then after it cranks it goes to a little over half then starts to climb does any one know what this might be? what i need to check? i am ](*,) with this thing

thanks
william