Have fill the crankcase up for that to happen... Talking 6-6-7 gallons of fluid..
unless the crossover cracked into a bolt hole connected to it. then it would just weep out the head of the bolt since the mid plate is rtv'ed to the back of the block and around the bolt holes. looking at the mid plate on teh block side, if an o-ring let loose, it would leak out one side or the other through some open areas casted in so i dont see it getting through a bolt hold.