Ok AK folks, tell this new-be what I need in the way of spare parts. I keep spares for most of my fire arms.  Firing pins, extractors and springs etc.  
I have a Yugo under-folder which has quickly become my favorite gun.  I don't want to get to the range and have something go bad or break and I don't have a replacement. With 700 rounds through it so far there has not been a hiccup or skipped beat so maybe I don't need anything?  This thing is built solidly, and all the parts seem stout, but I like to be prepared.
Also, do any/all AK parts fit my Yugo?
I sure enjoy this site and thank you all in advance for any info.

AK's were specifically designed to NOT break, and most live up to that.

For "just in case" parts, I'd recommend:
Firing pin.
Firing pin retaining pin.
Extractor.
Extractor spring.  (More a risk of loss then breaking).
Extractor retaining pin.


Unless defective from the get-go, there's really not much else that ever breaks.

Quoted: AK's were specifically designed to NOT break, and most live up to that. For "just in case" parts, I'd recommend: Firing pin. Firing pin retaining pin. Extractor. Extractor spring.  (More a risk of loss then breaking). Extractor retaining pin. Unless defective from the get-go, there's really not much else that ever breaks.

Agreed.  Those small parts get an amazing amount of abuse thrown their way.  Hence... they have the shortest service life of any of the parts (extractor assembly mostly).  I carry the same for my AR15 (as well as an ejector seembly and gas rings, JIC).  

just get a spare bolt assembly (or 2), a spare FCG, and a spare recoil spring, and you should be good to go.

Thank you all three for the help.  I think I now have an idea what to get.