Dipping vs blasting

Chrysler didn't prime or paint the boxed in areas before they put the car together or painted them did they? Would it be the same unprotected bare metal?

The entire body went down into a vat of primer, and the boxed in areas have holes to allow the paint in and back out. So they should all be painted inside.

http://www.valiant.org/valiant/sinclair/sinclair-11.jpg