New Cummins ISX Upper Repair Insert. 
This insert will press fit into the top / upper part of the block to prevent the liner from being able to move around and give the liner some stability at the top. 
Similar to how the Cummins N-14 Liner press  fits in the block. 
Insert Dimensions
6.540 O.D
6.339 I.D ( finished size I.D after install )
.400 Height
Price is per insert
 
Part # LS-ISX Upper