LS1 into a 73 cheyenne

[smokedat]

There is no difference between the two heads. The numbers tell what original mold the casting came from. 243 mold was done at GM Research, the 799 mold is used by other vendors. The same vendor will have 243 and 799 molds. The numbers are just a GM system for when the mold was made. If a head had a problem it helps them track down where the problem started. The only difference between the heads is production variance.