Bill is correct!
Most of the time it (ammeter) will be 'peged' & of no use anyway. It will only last till there's a big load (low battery), then It's 'toast'.
I would use a 12V 30A Generator to keep the 'orginal' look. You ONLY need an Alternator if runing A/C.
These (high amp) Alternators are made for cars/trucks or Station Wagons with a lot of electrical acessories (power windows, rear gate) and A/C.
The only (other way) would be to rewind the orginal ammeter to handle the load, which is to costly.
Happy trails.
