He is going to purchase the module this week and starter to take those out of the equation. The alternator has a red and white wire plug thats in the alternator and 3 red wires on the terminal. Battery, red wire from the plug but have no clue what the third wire is. It could very well be connected wrong. He didn't remember how the wires went when he removed it, nor did I and we forgot to take a pic. It only has that terminal, plug, and a bolt on the back left.Whut up with that alternator regulator wiring? I see the plug but it's not plugged into the alternator. Not that it has much to do with your start issues, but it appears there's been a lot of monkeying with the wiring. Trying to do that one-wire alternator thing? Usually it's only done for cleaning up the wiring but that means getting rid of the regulator wiring or hiding it. Not needed on street driven stock or stock-ish cars. It appears there has been plenty of wiring re-routing or taping up or whatever in the past. Not that it's bad, but 37 year old harnesses don't like to be messed with much. It's not like the G-body doesn't already have a reputation for crappy wiring systems. JMO.
If the engine cranks and you got fuel but no fire, the ignition system is where I'd start. As mentioned, there's an ignition module inside the distributor that sometimes gives you a warning it's going away (by engine dying at random times, but then restarting when cooled down). Sometimes it gives no warning and gives up the ghost. Result? No firing to the plugs. If you do replace it, make sure to get the right one. They have 4 prong and 7 prong ignition modules.
Check the wiring as well as mentioned. Any breaks, especially if it doesn't break through the insulation, can be a bear to track down. Is the coil firing? Are the connections from the battery terminal to the coil working? Make sure to put the grounding bracket thingie (name escapes me without coffee) for the coil back in place when changing the cap?
If the engine is spinning over while starting, the solenoid is working properly. If it wasn't, the starter motor would spin, but not engage the flywheel and the engine wouldn't turn over.
I think there may be a bad starter motor here. Just my opinion, to go along with the heat soak problem previously mentioned. Replaced other stuff like an alternator and cap and rotor. What's more money spent, right?
If you need one, in 1983, the original starter motor would be part number 1987287. Delco # 383-313. I haven't seen any on a cursory search, but they may be out there somewhere.
You could use 1988721. Delco# 383-284. It's still available in some places. Although Delco says it's obsolete.
Of course, there are the aftermarket rebuilt units but you can use the above numbers for cross-referencing.
Good luck with this. Elec-testicle issues aren't something I'm very good at.