what would cause dodge 318 to shut down

A lot of things could...god forbid...a broken timing chain...a fuel pump failure...insufficient ground connection to the 1/0 battery cable leading to ECU failure...if you can find out the diagnostic report may help...air, fuel, spark, timing....valve timing....please examine all these things for proper operation or give us the report not certain that yours is an OBD- II (would have to investigate this) but in case you could get a $20 scan tool~

Okay yours has a distributor...excellent, we can check for 12 volts at the coil...as far as the OBD-....there's a downloadable manual on how to extract any trouble codes

take the distributor cap off....if it the rotor does not turn when you turn the key....that's going to be all she wrote...sadly~.....you'd have to disassemble the motor and take inventory of what can be re-used~