They're 194's
Try here for an LED replacement. WLED-WW5 is suppose to be a good color match for a white incandescent bulb. I swapped out all mine for them but in red. The 5 in the part number is for the number of LEDs on the bulb. You need that one for full light spread in the gauge. http://www.superbrightleds.com/specs/bulb_specs.htm#x5
Swapped mine out also for red, to bad the tach and speedo bulbs are sealed inside.
What the heck are you supposed to do when the bulb goes out?? Buy a new gauge? Stupid!
Haven't had to do it yet but I agree with changing all 4 bulbs cuz the new one is bound to be a wee bit brighter or dimmer than the others which would be irritating to the eye.