I worked as a quality control on the production line at the Ford Motor Co. This was many many years ago. I was the QC at the end of the chassis line the pant had four departments body, paint. chassis and final or trim. The main structure of the car sides top floor doors hood trunk were all assembled in body. Then on to paint were the whole car would be dipped in caustic chemicals and then painted. Next off to chassis where the drive train and everything except seats and trim were put on the car. When it reached me it was already to drive away only needing a slip in chair. I noticed that the superintendent of production and the superintendent of quality control were both standing around which was a little odd but I went on with my job. One car came down the line I did my normal check of seeing all repairs had been done on the car and a walk around to have a last minute check off all the fits and then gave it the OK the superintendent ask to check it again when he said that I knew I missed something. This time I carefully walked around the car looking to see what I had missed but came up with nothing. The superintendant walk me to the back of the car and said check the tail lights when I did I seen they were different which is impossible unlit I realized that this was two different cars. In the body shop they made a mistake which put two different sides on one car and it had got all the way to me. It was a long time ago but I think the cars we were building were the Falcon and Pinto at that time so when I walk to one side it was a perfect Pinto and when I walked to the other it was a perfect Falcon. I was a little embarrassing for me because I thought I was doing a good job.