its not worth the stress of worrying about it these motors are so well engineered, even IF they crack, you can drive them for years (if you seal the crack with JB weld or monkey dung or chewing gum, you get the drift) I made the worst move in memory by selling my '99 that was in showroom condition,5,000$ trans , lifted, big tires, all the usual engine work, (turbo,exhaust, injectors fuel box,etc)loved the truck, BUT, crawled under it one day and BAM! there was the dreded 53! me being a maintenance freak and a worrier, I just couldn't get past the horror stories of blown 12,ooo$ motors, so I sold it with only 91,000 miles on it, the dealer sold it and knows the guy personaly, he now has over220k on it, no problems (I miss that truck) so even if it does have the 53, dont obsess over it, better yet, dont look for the "53"