Welcome to the GMForum. Always good to see fellow GXP owners. You can go through the Northstar Mecahnical Pages and get a good grip on common problems. Oil crossover lines and the IM shaft are two of the very common ones.
Is it a oil or electric smell. I was getting a small electrical smell which quit when I changed my battery from OEM. It died just before I covered it for the winter 6 years old. I knew it was going when the voltmeter stayed around 15v all the time. Battery wouldn't fully charge anymore.