I used to work for a truck wrecking yard. Valley Truck Parts and Equipment. They run across the 4BT's every once in a while. Call them at (800) 598-5715 and ask for Dennis. Dennis is the engine expert. Don't talk to anybody else. He's like the Marlin of Diesel engines. Tell him that Dave Case told you to call. If he doesn't have one, and he can't locate one, he will have some places that you could try.