...product year.? I own a 1970 442 W30 4spd (1 of 1032). I have deciphered all numbers, castings and codes with teh exception of one item. On the Fisher Body broadcast card under the heading of SPCL (special?) is the letter "Z". This same code is on the cowl tag in front of the trim code Z 930 (Black Buckets). What does the "Z" stand for?