If your bulbs continue blowing out I think I know your problem, I'm assuming you're replacing these bulbs yourself. I'm also going to assume you are not wearing clean rubber gloves when removing the bulb from its packaging and installing on your truck. If this is the case then that bulb is getting covered with the oils and grease that is on your hand from when you scratched your balls earlier today therefore causing said bulb to burn out.
2001 - 1999 9004/hb1
The circuit breaker for the headlights is intergrated with the headlight switch.
Remove the headlight assembly to gain access to the bulbs.
There are two screws in the tailgait jamb, just remove them and the lense comes right out exposing the bulbs.
Short in the wiring is the most likely cause.
I have a 2005 1500 and you have to pull the whole assembly out. There is a bolt that is really hard to get to on the bottom!
One or more headlight/taillight bulbs are inoperative.
gmc 1500 sierra was fuel injected in '92
The 2007 GMC Sierra-1500 has 16 valves.
The 2010 GMC Sierra-1500 has a V6 engine.
The 2006 GMC Sierra-1500 has 12 valves.
The 2004 GMC Sierra-1500 has 12 valves.