My 1997 CC Allure has a PRXB Pacbrake, exhaust brake which replace the original sometime around 2005. The coach now has 67000 miles on it of which I have put about the last 36,000 on it. The engine ...
It is possible for them to wear out to the point they leak so much that they dont do much but that is very rare. I would be more inclined to make sure the torque converter is still locking up.