It's a safe bet that all IBM 1390120 and 1390131's made before the middle of 1986 or so will have this. I'm not sure about the industrial, but I imagine it's got it as well.
Basically, it just indicates an older model keyboard, which is usually sought after for other reasons (barcode label, older = better, thick plate, etc.)
Industrial varies, actually, it turns out. The actual proper industrial models are identifiable by their extended temperature range components. In some cases, that means the 4 pin oscillator, while in others it means an extended temperature range can crystal. As I said: there's no functional difference between the two. They're both +-100ppm or +-50ppm parts depending on controller version, though the oscillator (4 pin square) typically has a slightly wider temperature range.
The annoying thing is that I've noticed some of the oscillator controllers use the SAME part number as the controller PCBs. I don't know if that's because these PCBs support both - though I've never seen a can setup that can also accept the oscillator - or because IBM just said "screw it, let's not give it a new PN."
I also have two boards with the crystal oscillator as well, one is a 1388032 (17 DEC 1985) and the other is a 1390131 (17 APR 1986), both made in USA. Actually, my two keyboards have the EXACT same controller boards. Maybe back then they hadn't cheapened down the vanilla model M to the extent that they really needed to have a separate "Industrial" keyboard.
Most examples of the Industrial I've seen have the range extended on the LOW side over the high side, as the stock / base components are more than sufficient for the high side. If you check the capacitors, the temperature rating is already on them - and it's usually 85C. That's the typical range for computer use capacitors, and far above what you'll see in even the power devouring hot running M13's. They only had to make some minor swaps to get the low side down to prevent component level hysteresis - crystals tend to lose accuracy or fail at temperatures below normal operating range.
Because the M is a very simple design to begin with, the baseline is already very near industrial range and extended temperature ranges of -20C to 70C. The weakness is at the component level on the low side - a frozen M works fine mechanically but fails electrically. (Can't say the same for a Cherry MX of any flavor. The switches themselves will likely fail due to metal contraction.) Swap a few components on the controller so they don't fail at low temperatures, and you've got a near everything-proof keyboard.
Yes, this is also why most modern harsh environment keyboards are rubber dome. It's more resilient to temperature swings, liquid intrusion, dust intrusion, and so on. Rubber dome doesn't care if it's -20 or +100. But neither does buckling spring.
