not quite, the strongest 24 valve blocks have the number 6 real big on the drivers side of the block followed by a lot of smaller numbers, no not the ID numbers found toward the blocks rear, these are right next to the inch tall "6". these blocks were mostly found in generators, cranes and other heavy construction equipment. very rarely are they found in a dodge truck, ive only seen one(and stupid me sold that truck
) a lot of hard core pro pullers look for those block because the wall thickness is atualy .056 thicker then the truck version as to allow for the extra duty these blocks tend to recieve. interally, everything is interchangeable which allows them to build a powerful realible block. Ive only found a couple of these blocks sitting in junkyards or on ebay as most of the applications they were put in are still in use today. the 54, 55 and 56 series were a little thicker in that weak area wher the 53 is prone to crack. Also, just because you have a 53, doesnt mean itll crack. 3 out of 4 of our trucks have 53 blocks, noe have cracked yet and all are over 120k miles on them, mine making 500 dyno proven hp and 219k miles. less then one percent of the 53 blocks made actually cracked. according to TDR, only those blocks with a thickness of .253 or less were prone to cracking, most were .254 or thicker and have never recorded had a crack like the thinner versions. if you want to find out how thick yours is, pull the motor, and drain the block, then remove the freeze plug from the 3 and 4 cylinders and take a diacaliper and measure the external wall thickness and the water jacket thickness, .253 or less, you may eventually have an issue, most crack between 90k and 130k miles if you get .254 or greater, you can sleep a little easier.