I read somewhere that a stamped # on the block possibly "53" or in the fifties indicates a good or bad casting.some were ok some had issues. I can't find where I read it and wanted to update my notes.Can anyone help?

 

The "53 block" is prone to cracking but its for later model trucks only.

 

Yup ^^, what he said. I have a 2000 with a 53 and am less than concerned about it cracking, if it does it does.

This will tell you all about the 53 blocks.
http://www.stamey.info/Truck/Cummins53BlockFAQ.htm

 

yup, the 53 block was only used in 1998+ 24 valve engines and very few 12 valves at the end of their production.

 

From what I have been told a 12v "53" block is thicker than a 24v. They made them thinner to promote faster warm ups.

 

I've got one of the oddball 12V 53 blocks that I use for mock up and fabbing. Don't see any cracks, but pretty much all the pistons were grenaded .