Jerry, the company that my dad worked for years ago bought over forty brand new 1983 Freightliners at once. They all came with 3406 Cats in them, They all had yellow engines but two, they were white. My point being is that if two white Cats could slip through in 1983 then it may have been possible for a couple of white Cummins to slip through in the early 70s. It is correct that tan would be standard, but if you had your heart set on white, I wouldn't be afraid to paint it white.