you've got a sturdy truck in the 97 12v. And although my cummins experience is limited, I would say hitting 35 ocassionally would be no big deal,. If I were you , i might open up the WG and take her for a lil' spin to see what you hit with it open. Better safe then sorry, you don't want to blow up your diesel like I did the first semmester of college...Hope this helps man