That would be the oil cooler that plumbs into the radiator hose and uses coolant to maintain a consistent temp. The one
@Dantra has is like the Hellcat setup where the cooler is completely separate and plumbs to an external cooler that uses ambient air. They put the oil cooler like the 300 SRT one on the 6.4's and HD 5.7's in the trucks so they must be worth something, but the setup off the TRX is the ultimate and probably more like what you friend is talking about.
That said, I have one of the coolant type oil coolers and have wondered if I could fit it up to my 90 degree adapter but haven't messed with it. Kind of doubt it will fit though.