When I purchased the radiator it came with some aluminum adapter fittings. I'm guessing here, but it looks like it adapts 3/4 - 18 (factory line) inverted flare to 3/4 - 16 (radiator). The radiator has a different thread pitch than the factory oil cooler lines which is why the adapters are needed. I looked in my drawer of AN fittings and found one that 'should' work. The thread size and pitch seemed to match up, but it appears that the fitting will bottom-out before going deep enough to engage the o-ring. Oh well, it was worth a try. I'll just continue to run without a cooler I guess. I like the cleaner look anyways.