Original as it came from the factory can only happen once in a vehicles life. That is when it is new and never driven.
At our car show we classify an original an a vehicle that is cared for and maintained an it was originally built. We consider original upholstery, and the car can not have been repainted over 35 percent of the body. It still has to have original style wheels and hubcaps.
My 1964 Chevrolet Impala still has the original seat covers which are starting to get a little worn in spots. If I would replace them with original style seat covers that would reclassify it as a restored to original even if that was all that was done. Otherwise it has been maintained with original parts and not modified from the original specs.
That is the great part of this hobby, what appeals to one may not to the next person but there is room for all of us. A lot of the satisfaction you get from an old truck or car is what you do to it yourself, whether it is to keep it the way it was built or not. I like an original vehicle myself, but others like to change them .
Jim