On my 2003 Tundra, one gauge light around the speedo went out, and then one HVAC bulb went out. Can I change these to blue bulbs instead of the stock green covers? They had blue #194 bulbs right alongside the regular ones I bought.

Any other options? All I really wanted to do was maybe make the lighting look a bit more modern.

Hey Brandon, you should be able to but you won't get that clear blue color that you have in mind, it will be semi blue with green. The reason for this is because there is a green filament on the speed face. I know there are threads about this on the 1gen forum because we have been talking about it for awhile (for some reason almost every member got intrigued by this idea at the same time) but here is a link that I had saved from a different forum that will explain it to you. It's for an STI but it serves its purpose for us since its the same concept.
Interior Color Change Tutorial: Gauge Cluster - NASIOC (http://forums.nasioc.com/forums/showthread.php?t=690378)