1972 Indianapolis 500 practice "B roll" clips

Purchased at an estate sale, this film was labeled "1972 Indianapolis practice," and appears to be "B roll" taken for a documentary called "The Man With A Wrench." But I can't find any further information than that to give any attribution. Some famous cars and drivers in these scenes that probably haven't been seen since 1972-1sh. Posted for historical information, discussion and critique.