I would suspect one or both of the fans. Once the motor brushes wear down and the copper wire it is attached to will contact the commutator and sparks fly. You won't see them because the motor is sealed.
Unplug the fan that is not working and see if the fuse still blows.
I would check the fan operation without running the engine to get it hot this way.
Remove the panel under the steering column and look for two green connectors. Plug them together, but do not make them click (they are hard to separate). Turn the IGN Key to run (NO START) and watch the fans. This TEST MODE will operate relays, solenoids, fuel pump, A/C compressor clutch and then run both radiator fans on low speed then high speed then off, and repeat the cycle until you turn the key off. Let it run through several cycles.
You will have the one fan unplugged, so only one fan should run low then high. If the fuse blows when it switches to high, then that fan is bad.
If that fan cycles low and high, turn the key off and plug the other fan in and turn the key on and see when the fuse blows.
Don't forget to unplug the test connectors.
Personally, I would replace both fans. 305k is a lot of run time for those little fan motors. I use Dorman and they seem to hold up good. One fan is listed for cooling and the other fan is listed for A/C. If you end up getting two with the same shroud, just swap the new motor and fan to your old fan shroud.
Let us know what happens.