Good info, but after all the reading on #53 blocks I have done I have come to the conclusion that there has to be more #53 casting molds than everyone thinks. Otherwise then whats the reason that the casting numbers can be found in more then one location, depending on the block? For instance the big 53 is usually found here but it may be found there, too. That has to be a clue why some guys with the #53 block have trouble with cracking and others can tow heavy and modify their motors with no cracking. There has also been some question as to the quality of some casts. Some look really bad around where the cracks form and others look clean. Not sure but I dont think that all #53's are the same.
'01 2500 Sport 4x4 5spd w/Fastcoolers, Mag-Hytec, EZ, 4" w/o muffler, Steering brace, aFe intake, 2 lo kit, Isspro Boost, fuel pressure, and EGT all on pillar, Westach Trans/Diff temp gauge in dash pod, Raptor 100 w/ 1/2" line, Pac Brake, Rancho 9000, 285's