They are 194s, but only for 2003 and older. Ford screwed with more small stuff again and in the 04+ cluster case, it results in the back of my cluster having 11 replaceable bulbs, 3 for my tach, 3 for my speedo, 4 for the upper row of idiot lights, and 1 shared for the fuel and temp guages.
I read someone using the 2721 bulb, so I'm going to give those a try. Nothing like spending $3.99 for a set of 2 bulbs * 11 bulbs = $24 worth of bulbs.
But I had 2 of the 3 speedo bulbs go out, the tach as 2 down and the single for the fuel and temp is toast too. I'd do LED, but I just don't feel like buying resistors, LEDs, and then spending my Sunday soldering - not after spending 92 hours at work the last payperiod (ended Friday) and then spending 3.5 hours (half hour commute each way) yesterday at work.
EDIT: 2721 bulbs work, so if you don't want to wire up your own LEDs or pay a crap ton for pre-wired LEDs just visit your local Checker/Schucks/Kragen/O'Rielly's/AutoZone/PepBoys for them. I paid $2.99 for them from O'Rielly's, I believe theu were 3.99 at PepBoys, and 4.99 at AutoZone.