Regarding the El Camino. Her eis a interesting tid bit. 1977 was the first year for corporate blue engines accross all GM lines.

This car has an orange 350. Early production cars had the orange engines as supplies of them were used up. I will check if challenged, however I believe the change over to blue occurred in St. Catharines and Tonawanda in the thrid week of Auguist 1976.