WELL IDF U SAY SO MY COUSIN WAS A CERTIFIDE AUTO AC TECH HE HAS THE PERMOT TO USE R 12 ITS STILL THE BEST REFRIGERANT . NOW DO U HAVR A 4 OR 5 BO;T AC COMPRESSOTR TE 4 BO;T WAS USED ON SMALL BLOCKS & the 5 BOLT WAS USED O BG BLOCKS . RICH TRYED TO DO WHAT U SAID & THE EAC...