Most manufacturer's of that era put "option labels" some where on the vehicle which identified all the various options the vehicle was equipped with...it's usually in the glove box, under the hood or on the spare tire cover. With those codes on the label, a Jeep parts dept can decode the codes and tell you what options came on it.
In years prior, many manufacturers used a "build sheet" which the assembly workers followed to see what options were to be installed on a vehicle coming down the assembly line...that build sheet was then placed inconspicuously in the last components to be placed in the car....sometimes inside door trim panels or up inside the front or rear seat frame cushion springs or on top of the gas tank.....not sure if that method was used in 1979.
