The first 500 had hatch scopes and aux scopes (like shermans) next to the blower housing, non movable. The aux scopes were discontinued when the smaller 400 cfm Rotoclone blower was replaced with the 1000 cfm which left insufficient space for the aux scopes. Lt Grimball's tanks in Op. Zebra in April '45 had the early models and two had the "new" dble pin chevron tracks. Korean War Pershings had only hatch scopes. Previous p-scope mountings were welded over and a round cap was welded over the weak spot.