Good looking report for your Duramax. How long has the oil been in service time wise? How is the truck used? You're no where near the lube condemnation limit for iron and the TBN is still pretty darn strong. I'd estimate without knowing more about the application that an additional 7,500 miles should be safe and likely if the truck is used for the next 10,000 miles like it was for this 10k then you'll probably be alright with another 10k.
Any makeup oil added?