Here is a glimpse of some of my collected chips.
While the first one on this picture is dated 83, ive seen a few 1982 ones.
(i must have got one somewhere, probably broken in a bin :)
So they span roughly 10 years in production, in various places in the world
Phillipines, Korea, Hong Kong.
Its hard to find perfectly good working pre-8580 SID chips, as the vast majority of them all seem to have defects in one area or another due to age or power on/off cycle stress. (higher heat dissipation?)
Sometimes its missing voices, missing noises, filter nearly silent, etc.
I try to capture waveforms and run tests the best I can with them. I've got
a perfectly running 6581R4 AR that I baby everyday (not pictured here due to its ugly "blurred in white goo" look)