blazer has spark at coil and gas no spark at plugs
If you have spark at the coil then you module is fine. How did you test spark at the coil? If you pulled the coil wire off the distibutor and tested there your coil and module are good. if you don't have spark at any of the spark plug wires then either you have a bad set of wires or distibutor cap is corroded, however you will usually not loss spark at all cylinders with wires and distributor cap. the most likely cause of no spark to all the cylinders would be a bad rotor. the rotor will affect all cylinders the same either with poor spark or in your case no spark.