When the truck is idling I hear a clacking that is louder than the rest of the motor. It has 72,000 miles and I doubt anything has been done to it on the inside. I dont really have time to pull it apart and check but if you guys think I need it I will. it seems to run fine other than that except for the low fuel mileage but I thin that will be fixed with the new trans tomorrow night. thanks

 

Don't expect a tranny to improve fuel milage.
Service at 105,000 miles is recomend. Since you have a concern, might as well get beyond the valve issue and do it.
Also check rear main seal while have tranny out. Not normal leak milage but will be lot easier now than say 20,000 miles from now.