The way I look at it, most (not all but almost all) 98.5's, 99's, 00's as well as some 01's have the 53 block. Check out ebay or craigslist and its not hard to find multiple listings for 98.5-00 with 200-300k miles on them. A lot of those trucks have to have the 53 block. The problem sucks if its hits you - kind of like winning the reverse lotto. But if it were hitting the majority of trucks these things would have a reputation like the powerstork 6.0's. It seems most of the crackage occurs between 75k and 150k. I'm just about ready to tip over 100k and no sign of problems. Its been the best vehicle I've ever owned hands down.

 

friend of mine has one....bone stock, 205,000 miles no crack