I have found that after using silicone sealant all around the plug and connectors that I have not had a problem with mine since march.

I went through 3 in one week and found that they seemed to die when it was raining.
I bought them from auto-zone with a warranty and the guy there had a vette so he knew of the problem.
I put a new one on and then checked it and it was fine.
I took the water hose and hit it with water and started the car and it pegged the gauge.
I replaced it again and sealed it with silicone and retested the same way and it had no effect.
The area they are located is prone to have water drip down on them in heavy rain or a good washing. They sit straight up so the water just collects in the plug area. If it is relocated or the same sender is on other cars they do not sit stright up in an area that water can collect and sit in the plug area. I think that the water shorts out the sender.

I would like someone else to try this next time they have to change one.

If yours is still in the original location and working I would like to suggest that you get a tube of clear silicone sealant and seal it up.
You can do it without removing anything if you have skinny arms.
It may not work for everyone but $2 worth of silicone is not too much of an investment to give it a try considering the trouble you will go through if it does fail.

Anyone have any thoughts on this idea?
It is possible that I finally got a good one but the fact that I noticed each time mine failed the weather was bad.
The waterhose test reaffirmed my suspisions.