The "567BC" installed a water manifold and coolant jumpers to the liners inside of the air box. This solved the situation of the B liners which had the water passages around the bottom of the liner assembly. The C liners just have a seal to separate the air box from the crankcase. The BC still uses the B type heads (with their leaking issues), to my knowledge there is no such thing as a BC type head. C and newer designs use jumpers between the block and liner or head, eliminating the source of many of the leaking issues or at least making them far easier to identify and repair.

EMD had another solution, where the air box and top deck was removed from a B type block and replaced with a C or D type. This allowed the use of the newer heads that use coolant jumpers. These blocks have the square covers for crankcase access on the bottom, and round covers on the top for the air box. There is a rebuilt SW9 with an official EMD tag "12-567-ATL" with a 1964 date, and has the square bottom and round top covers. I'm not sure if that makes this a 567A that was rebuilt at EMD with a D top deck or ???