Congrats on the new Suburban. I also just bought a 1997 about a month ago. Here is what you need for your aux input. Easy to install.
http://www.amazon.com/AUX-INPUT-FOR-GM-PIN/dp/B001EAWOE0/ref=cm_cr_pr_product_top...
Man what a great job. Exactly what I want on my Suburban. Great job sir. I love the use of the stock bumper. Till I found the build thread, I was going to message you about it. I thought it might be hinge mounted at first. Very well done.