While inspecting the cooling spaces in my '59-60 B9AE block, I was surprised to discover three long threaded rods on each bank between the deck and bottom of the block. Had never before seen a hint their existence in any description/exploded diagram. Is this feature something related to the casting/mold process? Does every engine block have them? Or, maybe something strictly "Y-Block-related" to reinforce the deck? Found in all years, or a progressive development feature (like head posts)?

6 VOLTS/POS. GRD. NW INDIANA