1980 Chevy Truck fuses blown

Hello, which fuse is blowing, does it have a label, amp rating? My wiring info on your model year is limited, it shows the brake lites and taillights use separate fuses. Are you blowing only one fuse?

There may be a connector under the rear of the vehicle to disconnect all the rear lites. Unplug it. Use a testlite on the fuse terminals, instead of blowing all your fuses. If the testlight comes on, it's going to ground somewhere.

If I know which wire has the short to ground and it runs from front to back, I don't locate the short, I clip the wire front and back, leave enough of a pigtail to splice onto at both ends, run a new wire, Usually I just let the wire lay on the ground for testing. If everything works ok, then I worry about how to place the wire, so it is up and out of the way.