there are 6 illumination bulbs. I wouldn't change just one, but that one is probably the easiest one to change. you should be able to do it without having do disconnect any wires or the gear indicator cable. just remove the 4 cluster screws and pull the left hand side of the cluster toward you enough to get your hand behind it.
here's a picture of the back of the cluster. the black sockets are for the dash lights. the one furthest to the right (in the photo) would be for the fuel gauge. twist the socket to remove it. the bulb pulls out of the socket and is a number 194.
to get at the cluster, you need to pull the radio bezel out a little but, loosen/remove the plastic lower dash trim panel (4 screws) and 2 push-pins at the top corners, the 3 screws along the top of the cluster trim and a few screws along the lower edge of the cluster trim panel.
I recently changed all 6 of mine and the tach light burnt out again (next one over from yours) so that's what I have to do.
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