There should not be another fuse box anywhere unless a previous owner has fitted one.
A couple of things to think about for you.
Are they sealed beam headlights? This type of unit does not have a changeable bulb but should not be prone to blow if submurged in water due to the fact that the water cannot get inside. If the lights have been upgraded to halogen units that have a more modern H4 bulb they can let the water inside and if it contacts a bulb that is illuminated it has a tendancy to blow straight away because it is hot and the cold water cools it too quickly and, in some cases, can cause it to even break the glass of the bulb.
Another thing to think about if the units have been changed to later halogen type is that a halogen bulb will draw more current down the wiring to the headlights and can cause the wiring to burn out quicker. I had this happen to the nearside headlight on my 1969 109". It was easy enough to just run a new length of suitably rated wire accross and the job was done.
Hope this helps.
;)
