Bodies were bonderized before painting. Also, starting in 1948, the factory encouraged dealers to sell customers undercoating of the vehicle at time of delivery. There is a service bulletin on this from 1948 and in the case of Henry J's there was a memo issued prior to 1951 model year announcement date strongly suggesting dealers undercoat Henry J's before delivery (selling the customer the service). New cars delivered at the factory could be ordered by dealers & distributors with undercoating done in the courtesy garage area. It's listed in various confidential bulletins over the years. The factory info on new car deliveries at Willow Cottage is on the KFOCI HANDBOOK cd.