I think the factory was trying to eliminate the fabric covered wires in '53, but must have been using up old stock? Clearly, '53 was the transition year. My '53 Bel Air (an early to mid model year build) has most major portions of the mid-current main harness that are plastic insulated, but the high current and outermost sub-harnesses (eg headlight wiring) are cloth covered. I can't speak to the '53 AD trucks, but I am guessing the same - portions of the wiring harness in both styles - probably depending on when during the '53 model year the vehicle was built.
Last edited by drdoug; Fri Jun 11 2021 08:09 PM.