The actually core on a 2 core is 1 3/8" thick and the 3 core is 1 7/8", making it a 1/2" thicker. The mounting brackets on the side of the radiators are the same and the extra thickness in the 3 core should be to the front.
What I did on one rig was cut out and moved the radiator mounting holes on the body forward about a 1/2", but you might have to move your condenser forward also if the oil cooler is between them.
