Fusing between alternator and battery.

I don't understand the "4" business? 30 tho, will not be enough with a 50a alternator. I forget...........does the 65 have the separate large terminals in the bulkhead connector, for the ammeter/ alternator wires?
Thanks for getting back.
I just went to my garage and looked. It looks like there are 2 separate heavy wires, one is center left and the other is center right, both going to my bulkhead connector. One is to the alt. and the other is to the batt. Both are connected by shovel type blades and secured with screws. Is the ammeter wire connected somewhere to the alt. wire? All the bulkhead wires and connectors look like they're in really nice condition. I think the guy before me had to have replaced the whole shmear.