1975 for the HEI (High Energy Ignition) system (no more ignition points)
check the oil
2007
Coil
Replace the engine coolant sensor.
Your battery is dead.
Start with changing the fuel filter.
bad starter
most older trucks can be started without a key
Check and clean your spark plugs that might be the problem.
just do what i did and take out the tumblers that the key slides over.
The engine needs fuel, compression and spark to run. You are missing one of those.
Someone knocked a wire loose.