Re sprayed or dipped, I'm not sure about the older Jeeps, but the later ones were e-coated (dipped) for primer, then the body color was sprayed. The underside was bare e-coat. I presume a similar practice was used for the earlier Jeeps, but maybe less high-tech than e-coat. Net search reveals that PPG invented e-coat in 1961. PPG also claims that the first commercial e-coat of auto bodies was in 1976, which suggests to me that before that the bodies were sprayed with primer. Maybe the hidden areas were sprayed with weld-through, or not at all?