very veeird...
all the blocks ive blown to pieces, were all # 9 and #10 head bolt holes to get the worst cracks..
If you compare the 11mm and 12mm block side by side, the 12mm is thicker in those areas.. I have to wonder if maybe the alloy wasn't improved too.. After all the 11mm engines were the first shot at a diesel. And basically they are based on a (zipping up the flame suit) gasser block..
That block I welded only had 2 holes that weren't cracked..