Can't find specific information for the lamps used for the instrument cluster illumination---must not be looking in the right places.
FWIW one or two are beginning to dim a bit, not bad life for bulbs from 22+ years ago.
Edit: Please disregard---I have a NOS box of the needed lamps, been laying around forever and I'd forgotten they were here!
FWIW the Ford p/n is: Ford F4UZ-13B765-A. They're only $11 something each