I've looked at a bunch of 386 dies, see: https://www.righto.com/2023/10/intel-386-die-versions.html I typically use an earlier 1.5µm chip since it's easier to study under the microscope than a 1µm chip and I use "ΣΣ" because they are more obtainable. Typical steppings are S40362 or S40344, whatever is cheapest on eBay.