Of the non-surface mounted 5x86's, it appears there is the ADH, ADY, ADZ, and BGC models. My understanding is that the chips were manufactured through 1999 although I've read some reports of later dates (it seems AMD manufactured other 486's into the early 2000's).

Is there a general consensus on which of these models and/or which production dates are most reliable at higher clock speeds?

As far as I know a few of the early chips were on the 0.5 micron process but the vast majority were on the then-AMD standard 0.35 micron process. So I'm guessing that's not much of a differentiator.

Is it a crapshoot or is there any science behind it? 😊