I once had a 75 LeSabre that had the build sheet in the driver's door, taped to the tar-paper cover on the inside. I found the same sheet on a 74 LeSabre. I can't remember which factory the cars originated from, but I do remember it was the same.
It was not a rule that the build sheet would end up in the car, the rule was that it was dropped in the paper bin at the factory.
The build sheet for my '76 Electra was tucked under the springs in the rear seat. You can pull the seats out by pushing the base of the seat towards the rear of the vehicle. Do that on both sides and look underneath the seat. I had a limited, but I'm sure a Park Avenue would be similar.
Before I sold my '71 Centurion...I found a build sheet in the trubk, stuck right behind the back seat, never touched. Left it there...hopefully the new owner fround it!
