I figured I'd delve into the various part numbers on Yugos. I've heard it all from "Any gun that has a part numbered component is a refurb!" to "The Yugos used P/Ns on their new stock, if you have P/Ns on your gun is unrefurbished!"
I don't think we can answer the question as to whether they were used during initial builds or not, but we can take stock of them and see what they and maybe see some variations with them.
The first thing I noticed was the bolt carrier. I'll be damned if the M59 and M59/66 don't have different part numbers:
Also there are M59's with variations on the P/N format: 0-00004
Next we move to magazines, there was only one number: SL-4-00.000
But wait, they also etched it on the side?
Trigger groups had etchings: S-00.001
And engravings? Yes it appears so!
Receiver covers were stamped: 0-00.005
Gas piston: 0-00.003
Takedown levers even had a stamp: S.1-03.100
Bolts had an etching: 6-00.001
Firing pins had an etching it appears: 6-00.002 wait a minute, 6- for bolt and pin both must mean that 6 is the sub assembly group for the bolt, neato!
(I don't have any photos of one, but I bet the extractor might have been 6-00.003)
Gas tube: 2-00.100
Handguards even had a stamp: 2-00.001 (Yup, that first digit 2 is a sub-assembly designator just like with the bolt)
Next comes the buttplate with this little stamp (no idea if there is a number inked on the 59/66 butt pad, but again sub-assembly 3- for the stock components, I bet the crossbolt has a 3-00.00X number as well): 3-00.002
and last but not least, receivers had a P/N stamp: S-102.000
There may be others like sight ladders, op rods, bayonets, etc. but I don't have photos of them. I'll post more if I find them, but I thought it was interesting to see some of the different numbers and variations and get them down on the site so our membership could start comparing the numbers they find and see if we might turn something else up.