2002 Trailblazer with vibrating engine

Hello, I hope someone has some ideas for me. I have 2002 Traiblazer LT EXT. I bought it 6 months ago with 28,000 miles on it. I had a Trailblazer LT that I bought new in 2002 that I traded for this current one because I wanted more room. Anyway last week I was driving my kids to school when I noticed as I came to a stop sign my steering wheel was vibrating.
I turned down the radio and could hear it too. This went on for two days and then I contacted the dealership I bought it from. They weren't very helpful and I eventually went to a different dealership that said they would take a look at my car. I have 36,800 miles on it now. My original dealership would not do anything for me because my warranty was up. The dealership that has it now is honoring my warranty and really being helpful even tho I am pass it by 800 miles. Anyway, today they started looking for the cause of the vibration and have narrowed it down to something deep in the engine. They say that either my engine will need to be rebuilt or replaced. They aren't sure yet what is going on and tomorrow the service department manager is calling GM to find out where they should go from there. They are now telling me there is a slight chance that this won't be able to covered under warranty.
Does anyone have any advice for me or any ideas on what I should do?

Thanks,
Corrina