I know 'numbers matching' can/does mean different things to different people. On my '69 300 vert, the VIN, motor and tranny all match. So on a base level, I have a numbers matching '69.
But to go deeper, how would I tell if I have the original carb? Date code/stamp somewhere on carb? How about the rear end? And any other parts that have some type of markings that indicate the part(s) are original to the rest of the car? Thanks!!
Original or numbers matching as you point out means different things to different people. In some cases, matching numbers means very little to a cars value while other times it does. Who cares about a number matching 1965 Rambler 4-door? But a numbers matching Hemi 'Cuda is a big deal. It boils down to the rarity, collectability, and demand of the car and current market pricing.
Those cars deemed collectable with the lowest original unrestored miles, garage kept, not having parts replaced, still owned by the original owner, having its original documentation from the day of the sale from the dealer, and other related materials will pull the highest values - and very few cars fall under this heading.
The next class of cars which on another forum we call "Day 2" cars are those that are mostly original, but enjoyed and driven - which many cars fall into this category. It is mostly original, meaning a numbers matching engine/transmission/rear end. Parts may have been changed out to keep the car running as the case with most cars. They did not have collector value like they do now, so parts got replaced or swapped and you tossed out the original. Might include hoses, radiator, carb, exhaust manifolds, distributors, Alt., starters, etc.. These cars are original, and show all the signs of wear you would expect from a car that is driven and kept running after all these years.
Then its a free for all from that point on as to what the seller and buyer perceive as meeting their requirements as to what is original, what is not, what has been modified/replaced, and if it has been refurbed or restored.
For some, original is not key and can yield a higher return than original. The 1965 Rambler with a blown Hemi will pull a bigger return than the same car with an original numbers matching 6-cylinder. This kind of car would be of interest to the "Dare-to-be-Different" crowd and would probably sell at a much greater profit than if it had been original. You see this in many of the car build shows on TV, it is all about making a profit and doing it in a way that they can entice a buyer.
With the aftermarket industry, many of the cars seen at car shows are "Clones," "Tribute Cars," or "Recreations" (the newest buzz word) of an original model muscle car. Lemans & Tempest become GTO's and you would think that every GTO produced from 1964-'66 was a 4-speed tri-power car. Malibu and Chevelle base cars become SS cars. The 318 Mopars become big block or Hemi RT models. Mustangs all have the hi-po 289's or resemble the "Bullet" or "Eleanor" cars. Then of course there are the steel bodies you can buy and then build from the ground up suited up any way you want. These cars are not original, but they still command high selling prices because buyers are willing to pay "less" to have a clone than what they can afford in buying an original.
The condition of the body prior to a rebuild or restoration can for some be key. Original means that, all the panels are original to the car with correct date stamp codes and part numbers while others could care less if the entire car has been re-skinned from a rusted away hulk sitting in a field for the past 40 years which may not hurt value with some cars when it comes to a 1 of 2 type car or if the rest of the car is low mileage and still original number matching if a muscle car. Fewer and fewer cars have their original panels as rust and rot gets to them. So how many can actually claim that they are original anymore?
The trend now with regards to many GM cars is to slap in a late model LS engine in place of its original powerplant. That's what the younger generation want. So more and more original muscle cars are getting the transplant. It does not seem to hurt value and may actually increase it BECAUSE there are younger buys just looking for that kind of a swap. Other upgrades are the 16-17-18" rims & tires, 5-speed and OD automatics, coil over and tubular A-arm suspensions, disc brakes, stereo upgrades, and other personal touches. Essentially, the original flavor of the body/name is kept, but everything under the skin is changed to "upgrade" the car to 21st century driving pleasures - because this generation is not mechanically inclined nor care to get dirty rebuilding a carb, tuning an engine, installing ball joints, doing a brake job, or anything else. With the modern upgrades, you can get serviceable parts and most current auto shops can repair & fix them.
So original numbers matching cars will matter less and less as time goes on. It may matter to select low production cars that are ultimately museum pieces or trailer queens that go on display at assorted venues and compete for trophies. This latest generation is looking for that
nostalgic romanticism which the car's nameplate symbolizes and has conjured up within the car culture community. Except, they also want the car to perform, handle, have interior comfort, and electronics like today's modern cars.
I say don't get hooked on original matching numbers car if you plan to enjoy and drive it. It may be of help for insurance appraisals, but it really is not that important in the overall scheme of things. It can of course be helpful in rebuilding some assemblies like the carb, but it can also be cheaper and more cost effective to simply replace old with new and be done with it.