I had to have the dash vents on my 1997 Dodge truck repaired last month for almost $700. Apparently the vent door would not change from defrost to panel setting. The vacuum check valve failed and allowed oil to enter the vacuum lines to the HVAC system and ruin the vacuum door-actuator. I looked for a service bulletin on the '97 but only found ones pertaining to '96 and '98. Seems strange that they skipped a year on this problem. This doesn't seem like a normal maintenance item to happen to a vehicle with less than 62,000 miles that has been garaged and well maintained. Has anyone else had this type of problem on a 12-valve engine? I am concerned that, even though the Cummins engine has a good warranty, the rest of the truck is going to eat my lunch in high dollar repairs. I did not feel comfortable tearing out the dash to fix the problem on this episode. 
