Just to complete and close this thread:

I found somebody with the right informations for me:

The ammeter is from a 1964 - 1966 Chevy truck.... wired in parallel with a shunt (cable)


1947 Chevrolet 3800 1-ton long bed
292 cui, GM 14 bolt rear-end, 4 x disc brakes
In Frankfurt, Germany
Pictures in the Forum Gallery