This is the set of UPPER and LOWER insulators for the 64-72  A bodies such GTO or LeMans.. 

   This set of 4 is for the 4 core.. it is 3.1/8" inches wide.. across the opening arch - & you get two upper and two lowers  as shown..

THIS SET HAS 2 prongs on each insulator.. and is NOT stepped at either end

Snip off the  tips on the insulators if not needed.

  (The 2 & 3 core is 2.5 inch's inches wide).