[mockingbird812]

That is why I used the word "relatively". The bean counters at GM have to make projections on how many they feel the public will buy so the supply/support folks can ramp up to meet these needs. If they overestimate (which may have been the case with the 70 LS6) you will more likely see longer periods between casting dates of unique items (i.e. LS6 block) and the build date of the car.