American engineering why do they have to change bolt sizes on the same part! 

yep unlike Americans for some reason designing crap with a 5/16 here then you're going up to a half inch there then back down to a 5/16 now going up to a 5/8 and then a half inch it's just crazy I find that a lot on American vehicles Japanese vehicles only need it seems like a few different sizes to take the whole engine apart and out