As far as the Z engs. check to see what the suffix code is on the pad at the front RH side.These motors had either a triple Z letter code or a double letter Z with the number 1,2 or 3 and so on.They also came with the center bolt valve covers and aluminum heads.Also check for the block cast no. behind the pass. head,above the bellhousing.Other engs. made across the border have ( Hecho en Mexico) stamped.Good luck,hope this helps.
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