I had seen some time back a posting about direction of cooling flow vers oil flow. I have a HTB -748 (electronic version of a HT-740 with a retarder). Anyways my cooler is a stand alone heat exchanger. It looks like a 6" pipe about a foot or so long. On each end it has a 3" fitting for water hose to be hooked up in line with water flow from discharge of water pump. (Series 60), on top (exchanger lays down) is two 1&1/4" pipes for the oil flow. No labeling on inlet or outlets. Some ones article mentioned lamater flow, (mispelled) some thing about if water inlet is on left then oil inlet should be on right or something like that. Any ideas, Thanks, Ray