Am hoping it’s just a blown fuse needed to be replaced

That truck will have a fuse panel under the dash on the firewall as well as having some fusible links mounted down near the starter. The horn is powered through the courtesy fuse. Then there is a relay and the horn switch under the steering wheel. The failure could be in any of them, The relay and slip rings are a common failure point on that vintage. To test the horns themselves just use a wire connected to battery positive and touch the connector on the horn. They both should blow. The relay is simple as well, when you push the horn button it should click if the switch and slip rings are good. If it doesn't the easiest test is to replace the relay and test again.