Hello everyone. My neighbor was cleaning out a shed and found these parts. The manifold ( PN 4F7087)looks like it would fit on a D318 but it's the heat exchanger (PN 4F7486) that has me puzzled. I haven't seen any 9Us around with this setup so is it off a road grader? We are along way from the ocean so I doubt if it's marine but I don't know. Here are some pics, any thoughts.