I dont have any spark

Check to make sure there is power to the coil. Check crank sensor (81 was some time ago. I think they started using them around that time).

Hi there you fine fellers. Which engine do you have? If you have the six cylinder, be sure the distributor is turning. If it's not, suspect the nylon drive gear is cracked. With either engine the air gap for the pickup coil in the distributor is critical. It must be.018" and must be checked with a brass feeler gauge to avoid a false feel from the magnet in the assembly. I found out from experience that it won't run with a gap of.021".

Not sure why you're monkeying with the battery and alternator for a no-spark problem. If the ballast resistor is burned out, which was common with the older dual units from the '70s, the symptom would be it runs fine until the ignition switch is released from the "crank" position, then it would stall. If you have the five-pin ignition module, (with four pins in it), and it's shorted, you'll get a single spark from the ignition coil when you turn the ignition switch off. Often you'll get a little jump from the engine or a backfire out the carburetor when that one spark fires the fuel in one cylinder.

You'll also get a single spark when you turn the ignition switch off, but none during cranking, if the pickup coil in the distributor is open. You can measure its continuity from the two-pin electrical connector at the distributor or right from the connector for the ignition module. Go by the wire colors to determine which ones to measure, otherwise I'll look it up in a service manual. As I recall, they will read somewhere around 500 to 800 ohms. If you have two pickup coils, one is switched in during cranking to retard ignition timing for easier starting, then the other one is switched in for running. A relay switches between them. That relay could have corroded or pitted contacts.

The next thing to do is what Jacobandnickolas suggested. Every dark blue wire under the hood should have 12 volts when the ignition switch is turned to "run". Check that at the ignition coil. If it's missing, suspect the dual ballast resistor. That was a common failure item, although the engine will run during cranking because the ignition switch bypasses part of that resistor during cranking.

Also check for 12 volts on the blue wire to the back of the alternator. If it's missing there, you have a wiring or ignition switch problem, both very uncommon.