
@KamajiNothing mysterious about it. Right up to around 1953 you would even buy a Ford or a Chevrolet station wagon with a wooden body from the cowl to the rear. This,as well as the name "station wagon" goes back to the time when a lot of people traveled by train,and the hotel driver or the chauffeur at their destination would meet them at the train station driving a vehicle with a wooden body that had a long roof with a tailgate that laid down and a rear window that swung up to make room to load suitcases and other gear.
Lots of resort hotels had them.
In case it needs to be said,these "station wagons" cost a LOT more than a car or pu truck cost,so owning one was a status symbol.
By 1953 the car manufactures had stamping presses big enough and strong enough to stamp out big steel panels to create station wagons and panel trucks with,and they were not only a LOT stronger than the wooden bodies of the previous ones,they were also lighter.
Plus,being made of stamped steel,they were a HELL of a lot cheaper to produce and sell than the mostly hand-made original "station wagons".
By the time the late 60's-early 70's rolled around lots of families with kids owned a stamped steel station wagon,so to "spice them up" a little to make them more desirable and easier to sell,the manufacturers created fake plastic "wood inserts" that bolted to the steel bodies. Besides being a LOT cheaper than the original wooden station wagons,they were also stronger and basically trouble-free. Which couldn't be said about the wooden-bodies cars that shrank or got swollen,the wood cracked,the doors and tailgates would no longer close,and there were gaps all over that let in the rain.
Plus,if you wrecked a wooden-bodied station wagon,it was all but impossible to find someone who could repair the damage done to the wood. What would have been a minor wreck in a regular car would be a total wreck in a wooden car.