As far as I know all the 5.3, 5.7 and 6.0 cranks are the same material. The early 6.0s have a thicker flywheel flange. LS6 cranks are all the same as the LS1 cranks. There is a different PN for the 5.3, 5.7 and 6.0 cranks, so something is different between them I just don't know what.