could someone tell me what the difference is between a 5.3, 5.7, and a 6.0 ls1 block. not the heads and all just the bottom end (pistons, etc..)

take at look at the gm engine and exhaust section thier is a post on everything you want to know

This link should be very helpful:
http://www.automotiverebuilder.com/ar/eb040538.htm