re: blazer has spark at coil and gas no spark at plugs
If you have spark at the coil then the problem is not the module. The module is what tells the coil to fire. I has to be the rotor or the cap, they are in a hard spot to install so double check they are in correctly and the cap is on tight. I have seen the top contact of the rotor get bent up away from the coil terminal inside the distributor cap cause no transfer of spark to the rotor. Your problem has to be the coil wire not puged in tight, incorrectly installed distributor cap or rotor, or by a long shot all of your spark plug wires are bad.