1954Chevy5Window,
The ammeter, per se, does not have a fuse. Basically, alternator output from the big BATT terminal feeds the ammeter post located behind the 'discharge' (-) side of the gauge while the 'charge' (+) side is connected to the battery via the connection on the starter.
All loads, minus the horn and starter, will connect to the common terminal with the alternator on the 'discharge' side of the ammeter.
There are few fuses on your rig...from the factory that is. To find the circuit that is blowing the fuse, pull all the fuses and reinsert them until you find the one that blows...that's the shorted circuit.
Does this make any sense?
Stuart