The fusible link will be a short piece of wire between the battery cable terminal at the starter and the engine wiring harness. There might be two of them on some applications, one to the ignition switch and another to the fuse block or the headlight switch. Look for a couple of small diameter wires bolted onto the big battery cable terminal at the top of the starter solenoid. Tug on those wires a little- - -a burned fuse link will stretch like a rubber band and/or have blisters in the insulation from the wire inside burning. Then find the short that's downstream that caused the link to burn. They don't fail for no reason. I use a low amperage self-resetting circuit breaker like a 10 or 15 amp, spliced into the harness, for troubleshooting purposes.
Jerry