The leather tanning process and materials 40 or more years ago was very different from what is the standard today. It is exactly this procedure that gave the leather interiors of those days that distinctive scent. Modern leathers are thinner, almost always have an artificial embossed grain patern, and definitely they don't smell the same, if they smell at all.
This is the reason that a car interior reupholstery, no matter how good, it will never be as good or as valuable as a well preserved original interior.