Try pulling the bulb and socket out of each guage and all out of the speedo. You may need to clean up the metal sockets for a good ground. I did this on my '75. You wouldn't believe how corroded they were. Pulled all out and filed the fingers on the sockets where they plug into the guages, then pulled the bulbs and cleaned the contacts inside. Wouldn't hurt to clean the base of each bulb while you're at it. If, by chance you have a F/G body, you may have bad ground on your dash panel itself. Test by running a wire from the panel to a known good ground. If the lites work, that's your prob. If not, keep looking!
'75 CJ5 304cid, t18 tranny w/granny low, model 20 T Case, DANA 44 rear, 30 front, 4" suspension lift, 33" tires, in need of more work!
"The only thing necessary for the triumph of evil, is for good men to do nothing." (Edmund Burke)