This my sound crazy but chevy offers two type of gaskets which goes below the throttle body on top of the manafold. one gasket is for 8500 pounds or lower the other one is for 8500 or above. The one gasket which is 8500 pounds and above has a has gap between the two injector holes where as the other on seperates the two holes. which one do I need for my fullsize 89 shevy blazer 5.7 350 engine??