I would offer the following as proof;
Take a peek at the Color photo that is floating around of the line in 67 where they are loading the rear into a 67 camaro body. The car behind the camaro is a BB full size, you can make out the black painted dip stick tube w NAT handle?
Guess it depended on the plant - those are VERY early 67's, and in '67, St. Louis didn't paint the BB dipstick tube - maybe Van Nuys did (it was received unpainted from the supplier).
The "Painted Parts List" was issued monthly by the Chevrolet Central Office Paint Standards Department to each plant's Material and Paint Superintendents, listing every part that required paint processing at the assembly plant, and what process each part required. The Material guys got it so they could intercept the parts that needed painting, and the Paint guys got it so they could segregate the parts by the different paint processes they required. This was an internal document, not issued outside GM.