The low beam headlights on my truck are only lasting 2 to 3 weeks

We had one truck in the lot that was blowing a low beam headlight once a week and it was rotating between the drivers side and the passenger side. We went through about 7 bulbs. Then as soon as it began it stopped. We haven't had one blow in 6 months. We didn't do anything to the wiring. We didn't find anything wrong with the wiring. In short I can't answer your question and ours solved itself.

 

Are you sure it's sealed good and and NO moisture is getting in there?

Condensation on the bulb will make it die prematurely.......same as the oils from your fingers getting on them that is another reason they'll die a quick death.

I noticed on the '13-14 crapcadias I drove if you don't carefully place the gasket before screwing the headlight housing cap back on it can pinch and bunch up in places under the cap causing a bad seal

 

Why don't you try another brand like a Sylvania or GE
Oviously the ones your using aren't any good.
Put a good brand name bulb in there , I've never even heard of grand central brand lol

 

Try a Sylvania or GE or Philips bulb
I'm sure your problem will disappear.

 

I found that the more expensive brands that "produce more light" don't last worth a rats ### in big rigs. they produce alot more heat and with the extra vibration of these rigs rolking down the hill the filliments snap prematurely. I tried Sylvania Silverstone ultra piaa extreme whites and a crap load more.... I spend probably 1000 of halogen bulbs.

if you want something that lasts

www.theretrofitsource.com and buy a plug and play 4300k hid kit (don't get that stupid blind oncoming traffic blue 6000k kit) your not in a Honda civic and 4300 puts more light on the road.

or you can buy the putco led headlight bulbs from alot of local aftermarket speed shops.

if you don't want either of those try another brand and maybe just a cheap one to see if it'll last longer.

 

Sounds like you've got a short somewhere.