Lets see some pics of your Cummins!

That on the side of the engine (fluid to fluid heat exchanger) cools the trans fluid when it's hotter than the engine coolant. It also warms the trans fluid to a minimum temperature when the trans fluid is cooler than the engine coolant (handy in really cold weather).
From there, the fluid flows to that heat exchanger up front (fluid to air). Just as the hoses connect to that up front, the fluid flows through those little H-pipe looking things. There, depending on the outside air temperatures as well as that of the fluid, the fluid will either go primarily through the cooler, OR primarily unchanged back to the trans.
It's all designed to maintain both a minimum and maximum trans fluid temperature.
in a nutshell paint thinner of the paint, (NO SANDING OR STEEL WOOL) then put a buffing wheel on your bench grinder and pick up some rouge bars at sears or your favorite over the road truck supply and get a bar stool and a nice tall glass of sweet tea and get to it, OH and some gloves that sucker gets very hot.
Dar
Dar






