For starters my truck is a 1996 12v 215 ppump, while doing some wok I figured I’d check the casting number as it’s a 12v and not 99-01 which had the blocks known for cracking it just so happened to have 53 stamped on the side of it. My ultimate goal was hp so I was wondering if anyone had any real info on these blocks. Iv been told “a 53 block is a 53 block” but it makes me question because if you compared 12v and 24v blocks side by side there is not only a visible difference like freeze plug size which means they obviously aren’t the same casting but also in design as the 12v were usually thicker. So maybe made in the same foundry but completely different castings.