I recently purchased a set of what i think are 993 heads. I took them to the machine shop and had them cleaned and checked out. When i went to pick them up the machinest said i had 487x heads.
So here is the mystery.....on top of the head the casting says xxxx993 but on the bottom inside closet to the intake there its cast with 487x the machinest says you go by the bottom number. the casting dates are between jan 72 and may 72.
So whats the real deal here ????
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