Pretty much what it says, our 2011 LT keeps blowing bulbs. Back in early march I heard the fast clicking, so I replaced the bulb (a little dark) and all was good. A few days later, the left rear went out. It's been fine since. Two weeks later and the right rear did the fast clicking again. This time the bulb was all whited out like a phosphorous explosion. Replaced it. Almost month later and last Friday it is fast clicking again. This time, the bulb had shattered! I replaced it again.
Any ideas what might be causing these bulbs to blow? A short or something?

 

Too much voltage, opposite of short. Must be some frayed wires somewhere rubbing together.

 

Has there ever been a trailer hitch installed?

 

Not that I know of.

 

How do you get too much voltage on a 12 volt system ?
My guess would be a bad socket(s) connection or ground. Causing an arc between the bulb and socket.

 

Not saying this is the problem, but are you sure you're using the correct bulb and not an "extra bright" one?

Also, I drilled holes in the housings for extra cooling.

Don't by the same brand bulb that keeps blowing. There can be whole runs of bad bulbs.

 

REAR turn signal.
By running 12 volts up the ground side. Short to voltage vs short to ground.

 

As mentioned, check for clean dry tight ground wires , burnt or melted sockets rodent chewed wire harness.

 

Oh yeah, I double checked the bulb packaging after the first one blew. Just the normal Sylvania bulb. I even went from AutoZone for the first package to Advance Auto for the second package.
I couldn't find another brand at either store, or I probably would have bought it.

 

Now that that’s out of the way, have you looked at the bulb holders?