matching numbers

[djbender@xxxxxxxxxxxx]

     When I read literature oriented around restoring American cars 
     "matching numbers" seems to be a big deal.  I think there are even 
     handbooks the afficionados use to determine which numbers should 
     match.
     
     I have never hear an Alfa person mention matching numbers.  In fact it 
     doesn't seem to matter, and often helps the value of a car to swap in 
     a better engine for example (larger, later, or upgraded components, 
     say to make a Normale look like a Veloce), or replace drum brakes with 
     disks etc.  Originality doesn't seem to be a big deal with the Alfa 
     croud.  I would assume however that when restoring something really 
     rare such as a GTA or a TZ that originality would become much more 
     important.  "Originality" can mean "original style" (i.e. having the 
     right type of headers on a Veloce), or "original to the car" (i.e. 
     matching numbers).
     
     Questions I have: is there a book or documentation stating how to 
     determine if an Alfa has matching numbers?  For which models would it 
     be important?
     
     Doug Bender

------------------------------