Hi I have a 98 silverado. I bought the truck a little over a year ago.. since I bought it, my passenger side tail light has continually shorted out. I would take it to a mech, they would "fix it" then a month later it's doing the same thing. I put a l.e.d. bar up under my tailgate, if that means anything to the problem. I'm sick of paying to have this thing fixed when I could probably fix it myself.

Was it doing it before the led install?

Do you know whether the problem was in your wires or the plate that holds the light bulb? If it is the plate I can tell they are notorious for this problem. I think the slot for the gets bigger or something and the bulb can't hit the contacts in the plate. I once pulled the wires on the bulb out a little so they can took the contacts and it worked for a few months. If you have a local junk yard try to find one or two plates and see if they work or just go to the local part store and get one.

This is a very common problem with GM products since before you were born.
The problem is two fold. First is moisture getting into the lens area and when water hits a hot bulb. POOF!
Second is the chinzy sockets that Gm has used for almost ever. Go to the auto parts store and buy a new socket and install it. That should cure the problem.
BTW is takes all of five minutes to change a tail light bulb on a GM pickup. Generally a philips screwdriver and a new bulb are all that is required.

I own one of these trucks and have had the same problem. Get the cheapest replacement light fixture that you can and install it in five minutes. Your problem will be solved

Also, take a look at the type of bulb you are installing.
If the base of the bulb is plastic, don't buy them.
Look for bulbs that have a glass base.
Dab some type of dielectric grease into the socket before installing the bulb.
These steps will help dissipate the heat that builds up and thus shortens the bulb's life.

I've tried everything that you guys have said, in the past.. I've changed lightbulbs, and the base, but that never solved the problem. And yes, it was shorting before the led install

When you say "shorting out," do you mean the fuse is blowing or the bulb is burning out?