I have seen posts here referring to "Preban Uppers" There is likely an obvious answer but it's not clear to me. All is understood as to what constitutes a preban lower receiver (serial numbers), but what constitutes a "preban upper"? That is, if it's an upper receiver assembly without barrel, what component within an upper assembly would be considered preban? Thanks for any clarification.
--RR

PS: if it's an upper including barrel with bayo lugs, flash hider etc... I understand why it's preban and maybe that's the answer to my question, but would appreciate clarification.

Your "PS" hit it right on the head.  The "Evil Assualt Weapon Ban of 1994" outlined those features, among others as being "Bad".  Either a flash hider and/or a bayonet lug on an upper constitutes a "Pre-Ban" Assault Weapon and may not be legally assembled on a post ban lower.  More info would probably be in the legal section.

Don't forget the grenade launcher!

Ok, yeah, I was thinking of only the actual "upper receiver" assembly being referred to as preban and it didn't make sense. Thanks for the clarification --RR