Started on the second truck with oil in the coolant. this truck has an e.g.r. cooler. I contacted the local dealer for gaskets to mount the e.g.r. cooler to the housing. They are telling me you cannot buy the gaskets seperately, you have to buy the entire assembly. Does anyone have a parts breakdown or part number for the gaskets? 2004 GMC T7500 7.8L Isuzu diesel.