When this has happened in my truck its usually the nut on the power connection at the starter has come loose. In your case you have also had starter work recently, which makes it even more likely. Just disconnect the large battery ground, and then crawl under there with the right wrench/socket and make sure that large nut is tight and has a star washer on it or a lock washer. That large cable has no fuse or fusible link, so don't risk working on it with the battery still connected.
Verify that the one or two power feed wires for the truck are also connected to the same starter post and that they are not broken. The wire on the other starter post goes up to the ignition switch to activate the starter. You should be able to see if the fusible links in those wires have burned, but that should not be a problem unless you had a short in the wiring. However, those wires run toward the back of the engine, and should be in a protective metal sleeve that runs up the back of the engine. If someone removed that sleeve there is a possibility that they contacted the exhaust manifold and it has burned through and grounded them. That sleeve gets in the way when you are trying to put the exhaust downpipe back on, so sometimes mechanics move it out of the way and then don't get it back on to protect the wires.
Bruce