AFAIK, they are still considered to be part of the LS family because the heads/cam are the same. the iron block is because they are more stout, and more resiliant to heat, so better for harsh commercial/industrial use that trucks see.
AFAIK, they are still considered to be part of the LS family because the heads/cam are the same. the iron block is because they are more stout, and more resiliant to heat, so better for harsh commercial/industrial use that trucks see.