There has been more hocus pokus about the cooling system on the 6.5 than I care to hash out

The GM update to the dual stats and high volume pump worked pretty well.....

Even the original single stat and standard pump was not too bad as long as the radiator was in good shape and the fan clutch was working right....

The rear two cyl's were set with .0005" (Half thou) more clearance on the pistons.....