The number 481S88 should be 481988 and is the block casting number not a date code. All W72 engines used in 1978 & 1979 Trans Ams and Formulas have the XX 481988 block. This block number was also used on earlier 1971-1975 400 blocks, however those did not have the XX letters. The date code which is 4 digits will have one letter and three numbers, is to left or driver side of the distributor. To date no original W72 engines used in 1977-79 Trans Ams or Formulas have been found with a date code later than Nov 1977 (K307).
Original W72 400 engines were suppose to have 6X #4 cylinder heads from the Pontiac 350 engine. What are the date code from the cylinder heads?
What is the engine block code from this engine which is located on the front passenger side of the engine just below the cylinder head. The codes used on W72 engines for 1978 were X7(auto) and WC(4-speed).
John Witzke
POCI/NFTAC Tech Advisor
1977-79 W72 Performance Package
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