Radiator Question

[rockman20]

Well I have had my truck for a while now and I am finally asking this question. (I am really bored at work and it never really bothered me enough to ask before)

The radiator in my truck is bigger then the stock radiator. I can say this with some confidence because you can see that the piece that holds the top of the radiator in place is not mounted where the stock holes are at.

The reasoning behind the bigger radiator is because there are 2 coolers, one on each side. The one side is my transmission cooler and the other side there is nothing hooked up. But the fittings are there and there is even a sending unit sticking in there like for a guage or something.

My question is, does anyone know what this was for? Was this a engine oil cooler? The truck originally had the 6.2L Diesel in it and it was the camper special as well. This appears to of come from the factory like this so I am just curious what it is.