I put blue LEDs in my autometer gauges to match the white face gauges I had installed in the instrument cluster of my 92 GT. The LEDs made them kinda difficult to read at night though. If it was done with white LEDs it probably wouldnt have been as hard to read. Also I did not use the Autometer LEDs. They had not come out with them yet.
Look for 194 bulbs in LEDs. I have the Sport Comp Autometers and tried out the Varad LEDs and those are bright, but don't have the spread pattern for good lighting. Trying a different pair I got off of ebay that has the side pattern as well. I will report back on the results, but as I see it, you need to look for LEDs with a light diffuser.