Starter motor sounds like a siren when you try to crank the engine?
Failed starter drive. Decades ago, you'd cram a new drive, new shift-fork, new brushes, maybe new front and rear bushings and a leather washer into the exisiting starter, and be good for another fifty or seventy thousand miles.
In today's world, you get a "rebuilt" or "new" starter, bolt it in place, and if you get a good one, you're good for 150K miles...maybe more.
Follow the Genuine GM service manual procedure to diagnose the codes for lack of 3rd Gear. Shift solenoids are common repair items, as are the wire harness for the solenoids, or harness repair at the electrical connector, or between the connector and the ECM.
