To help recover from high tooling costs, all car and truck manufacturers attempt to make items that can be used as long as possible. This is a great way for reducing costs per part.
Examples of automotive leaders in this field are:
The original Volkswagen Beetle bodies were basically the same about 20 years.
The longest run metal body is said to be the Divco neighborhood dairy and bakery delivery truck. Used the same sheet metal tooling over 30 years. Of course, more modern engine updates were added as the years passed.
Of the many General Motors sheet metal items that were repeated, a good example (maybe not the best) are the 1960 and 1961 Chevrolet light trucks. Between the two years few items changed. Yes, their ½ ton 6 bolt wheels and hub caps were very different, but this was the beginning and the end of the same item in that series. It is the grilles and parking light housings that were one year only items. As grilles are considered by General Motors as the vehicle’s front focal point, GM wanted to make the “change conscious” public realize they were buying a pickup that would show to others it was really a new model.
On the front of the 1960 and 1961 light trucks, there are almost no changes except for the grille and parking light housings. Therefore, these items can be perfectly inter-changed with even the same fasteners.