The links below will take you to three different YouTube videos.
The films were taken in about 1929-30 I would guess and the show how the wood was grown, harvested and processed into the body's frame. While along way in the past, it is still interesting to see how all this was done, particularly in Part 3 where they are making the parts and assembling them.
Small things to note are how unsafe the workplace was in those days. Little, if any safety equipment was used and no one thought much about it at the time. One ironic thing is a shot showing the logs being transported by truck. Is it a Packard truck? No sir. It is a Model A truck hauling the logs.
Please keep in mind that these are silent films. Also, while on the YouTube site you will notice a number of other Packard related videos, such as building the Merlin engines, testing Packards, etc.