I know I asked this before, about that panel. I found an old guy 75/80 at a Ford parts counter. Asked him about it, and he relayed the info. Absolutely sure now, that panel in the cargo bed is, in almost all '68, a footwell for the spare tire. In most there is a well there that was used for the spare, and Ford realizing the error of their ways, caulked it shut, but later, the caulk were away, so they caulked and bolted it down to prevent rust in the footwell left over from the wagons. He said (the Ford guy, about 70 years old) if that panel is there, most likely so is the footwell. Sometime in 68 model year Ford started taking out wells and still used that panel. They did that to reduce weight to start getting the muscle car preference. This Ford guy was really informative, such as half of the Rancheros came with a 390ci engine, again for muscle car.