I have a ser# 740-07-CB09446 that leaks from the aux relief valve. Over the past year and a half it's had 2 new o-ring seats and a whole new valve and it still leaks (not bad enough for the dirt not to be able to keep up though). Now I just had a sister truck come in with the same relief valve blown completely out of the manifold. Pressure values are from the factory and have never been changed. Anybody heard of this recently?