[DeTomaso] 351C Block Question

[bwerner at live.com]

Hi:  I was going through some of my 351C spare blocks today, and I found that I have a couple of blocks that don't have the X or Y cast into the valley area of the engines.  Anyone have any ideas as to why.  Almost every 351C I have looked at have that X or Y cast in many places in the valley area under the intake manifold.  Any Help would be greatly appreciated.  Thanks.