if you are still using the stock switch, it has built in protection for all lighting circuits
there is a bimetal strip from the bat lug to points at ''A'' and ''B'' when there is an overload the bimetal strip heats up and opens the points
the ''A'' points protect the stop/turn and tail light circuits, ''B'' points protect the headlights
the small fuse ''C'' coming off the stop/turn and tail light circuit, is for the dash lights and feeds thru the dimmer rheostat
the bimetal strip is the same as what is used in a modern day auto-reset breaker that would be on a headlight circuit
in an overload situation the strip will heat and cool rapidly making the headlights flash
with a fuse on the headlights once overloaded it would kill the lights, not good on a mountain road
flashing lights give you enough light to safely pull over
heaters and radios were options at the time and either had inline fuses or a 4 fuse panel on electric wiper optioned vehicles
not much else needed protection in a basic vehicle like our trucks
the battery hookup has a spare lug to connect a small auxiliary fuse panel, but don't overload the wire
your truck should also have a fusible link at the battery to protect all circuits in case of a dead short to ground or a massive overload
the bend here reference is if your lights flash under normal load, without an overload situation
the bimetal strip can be tweaked to increase the resistance, be careful when tweaking or you lose the overload protection
and you will let the smoke out of the wires in an overload
