Okay, pictures at 11. First shot is of the later style bucket. Note the large hole in the rear. With regular sealed beam lamps like they came from the factory with, there is considerable light that would leak back into the engine compartment.
The second photo is the back of my 71's buckets. As I remembered, they are more complete than the later style buckets, with only a small hole for the harness to feed through in the power rear through a rubber grommet.