I switched mine out with LEDs. The regular bulbs were hot and distorted the direction buttons to the point where one was non-functional.
The LEDs run very cool so no similar problem.
I posted a thread on how this was done. Just do a search. You need the correct value resistor and two 3mm LEDs. I wanted my installation to look factory original, so I did some extra steps that included moving some terminals on one of the boards. You could skip those steps by just placing a resistor in series with the LEDs in the wiring. Also I had a resistor for each LED. After thinking about it a little more, you could accomplish the same thing by just using one resistor that both LEDs would share (only one LED is on at a given time, so one resistor could be placed on the common power supply lead that both LEDs share).
You could also buy a LED setup from
www.wjoe.com.
Because of the heat problem, it's the way to go.