How much do 1947 and 2014 Beechcraft Bonanzas have in common?
The V-Tail Bonanza design was retired (for a bunch of reasons, many of them marketing-related), but the actual airframe of a modern Beech 36 Bonanza is, essentially, the same as the 1968 Beech 36 (and very similar to the 1959 Debonair, just stretched). You can trace a great deal of the design and parts back to the V-tail as well.

There have been some changes made to the design over the years (for example, the throw-over yoke is gone, replaced by conventional dual controls), but the bulk of the airframe parts are interchangeable because the designs are essentially the same (this is an advantage for Beech owners: The factory is still producing nearly all the parts you'll need for maintenance, because they need them to put in the new planes).



Most of the light GA aircraft produced by the legacy manufacturers (Beech, Cessna, Piper) are what are known as "follow-on type certificate models" -- they are the same production design approved back in the 1950s/1960s, with "minor" changes incorporated along the way. This means you'll find the same kind of parts continuity in pretty much all the major manufacturer's aircraft:


Most of the parts on a 1960s Cherokee 180 are the same parts you'll find in a 2014 Archer III (changes to the airfoil and panel layout notwithstanding)
Many of the parts on a modern Cessna 172S are the same as the 1965 172F (the year they went to electric flaps).

You'll find many common parts on the 172 going back all the way to the original 1956 172 if you look. Big changes were the swept-back tail fin (1960) and the electric flaps (1965)