just got a hold of an aluminum block

[George C]

actually there are a good bit differences in weight. alum 6.0 to iron 6.0 is around 90lbs, other blocks like the iron 4.8.5.3 have slightly more weight then the 6 litre blocks, of course the lsx is another 35lbs heavier then the standard production blocks

If weight is all you were worried about you didnt get much difference. 60lbs I think.