I wouldnt worry about the 53 block thing, I dont know what mine has and personally dont care, if it cracks it cracks and I'll deal with it. I love my 99 24 valve despite some issues that I have adressed to make it right again. First thing is the VP, just like everyone says, get a fuel pressure gauge. Relocate the lift pump to the frame rail, I used the Vulcan big line kit from Genos. Of course the exhaust temp gauge if you add a box, and from my experience, they work better with bigger set of injectors, and I feel better not tapping the pump wire by using a USB programmer. I just recently added the Lukes Link to rebuild the track bar, then the Maxx stabilizer bar links, and the DSS stabilizer, and my 4x4 handles beautifully. The only thing I am going to have to adress now is the fact that the bottom of my doors are rusting, I have been contemplating taking it to the local body shop I use and have them spray the gray on the bottom half of the truck with the bed liner stuff they use if they can match it pretty close to the orginal color