Numbers matching...What does this mean? Is a "numbers matching" vehicle one that has all date codes in the same year or within 3 months or_____? A definitive definition or the hobby accepted 'rule'or ?

if your 63 fuel injected corvette has matching numbers, that doesn't necessarily mean all the parts on the car are those that were installed at the factory the day it was built. the 63, for example, could have lost its original engine years ago. an enterprising vette dealer will search for a chevy small block engine with a casting # ending in 870 and cast a month or so before the 63 vette left the factory in st louis. he will then remove inappropriate stampings from the replacement 870's stamp pad and restamp the 63 vettes vin # and appropriate machine assembly date on the pad as well.the resulting 63 vette will have "matching numbers" in terms of its block, but it wouildn't be the original engine. For the most part, at least in the corvette world, matching #'s vettes are to be viewed as having replacement blocks. mike

There are some very good web sites dedicated to this topic. One that comes to mind is "Chevrolet by Numbers", "Camaro by Numbers" or something like that. Do a search on it.

I've checked out a few of them and have found that most mechanicals like engines and trannys should pre-date the body. The factory then added the VIN and trans type along side the engine block stamp. This gets real complicated and you are better off checking one of those sites for all the details.

"Matching numbers-what does this mean".....depends on the club and how they interpet the description and how they want to slant the results.
Your definition as to date is basically correct but also the casting numbers should be the numbers used in production and not those of later replacement parts.