I broke a crank in my 6.2 replace with 98 model 6.5 that engine developed a cracked cylinder wall. Now I have hauled home four 6.2 engines that were black in color,86 or newer? two piece seal blocks. I have found on all of the blocks to have cracks on the outer bolt holes of the main caps. I use the sub for some light towing of my jeep/racecar sometimes. Also want to build a diesel for my dually which does the majority of the towing. Are these block cracks something to worry about or should I continue to try to find a good uncracked block?