Mauro,
I like to drive at night, and the dim yellow incadescent 2v bulbs are not bright enough, so I replaced with LED bulbs, which will last forever and allow you to read how fast you are going. I chose bulbs that shine with a blue white tint, but I think they are sold in other shades. look up LED lights on the forum and you will see what you need. You need to leave a couple of incadescent bulbs on the instrument board to allow for enough impedence. Not sure where you can get them without shipping. Good Luck.
Mike