Tires and brakes.
If you haven't bought the tyres yet, I'd recommend the coopers if you can find them in your size. I had the BFGs prior to these, but the coopers came in at less than 50% of the price, I use them in 4wd at least once a week, have run into a couple of sharp kerbs here in Mexico, and have over 25,000 highway miles on them. They're still quiet and I haven't had to have them balanced yet. I'd recommend them to anyone with a suburban.
Congratulations on getting a truck with the rear brakes converted, I thought my guy was taking the piss the second time he told me I needed new rear shoes...again!
Looking forward to following your progress.
John