I wouldn't worry too much about the mileage if it has been well maintained and documented. 76000 miles is just getting broke in.
My 2006 Chevy has more than 98000 on it and it was maintained very well as a rental I have had no problems at all with it.
There is a informative thread in my signature about a RV on a Chevy chassis that may be of help. Be sure that when you ask questions about anything chassis related that you say it is on a Chevy chassis or you will get mostly answers pertaining to the Fords. As you can see from some of the answers.
Welcome to the land of Class Cs and a minority of Chevy Based RV Owners.