the sensor changes at some point, i think version 4 has the seal inside the box & version 5 & 6 have the seal as part of the sender itself, i remember having the remove the seal from my dccd box to fit the stock my99 foz gt sender (same as my99 gc8)

& yes there is a globe behind the light in the white faced gc8 dash, if you can't see your clock it will be blown