Identify the other ICs and work backwards.

The 8-pin says "3-544" and is probably a 73-544 clock gen. The resonator is
right there between it and the 40 pin'r.

AFAICT, the date codes for Q15 and for the relays suggest that it was
built as late as 9920. Is this confirmed by the date codes on the
other chips?

I've owned since about mid '98. The relays were replaced maybe ~'99. Don't
think the transistor was replaced, but might be.