According to the information provided in the FOIA request I made, my Armalite/Colt, Model 601 turns 50 years old Monday, 31 January 2011. It's already classified as a C&R weapon, but tomorrow it will be a C&R on both counts. It is has a "three digit" serial number as well as dual Armalite and Colt labels.
The 601 was shipped to the original purchaser on 06 February 1961 and spent most of it's time there. It then went between a couple of Dealers in rapid succession in the 2003-2004 time frame, and I picked it up in 2005. It's a basic 601 except that the furniture was replaced by one of the Dealers. I had it for sale last year so pics have floated around, and I won't bother to post any. It does not appear to have ever been shot very much by any owners, myself included.
No cake or candles planned.
ETA on 31 Jan 11 - The Dealer who replaced the furniture also had the metal refinished.