Coils were made by two manufactures, Essex and Prestolite. Essex reproductions are available and are dead nuts to the original. '66 to mid '68 were lettered differently than mid/late '68 to '71. The coil that MP sells is a kluge of later style coil markings. I carry the below pictured coils. '68 - '71 top, '66 - '68 on bottom.