D4 7U Radiator

Where is the best place to get a radiator core? I still have the oil cooler along side.

try rocore: http://www.rocore.com/
or general radiator: http://www.generalradiator.com/

As an FYI, in the past week there has been a discussion about blocking off the oil cooler lines and going to a full width core. When you call these places, you may want to inquire about the feasability of doing this and would the core be less expensive than a 2 core oil/water design.