The EMD two cycle engine was never going to meet the tier four requirements. They came up with a four cycle design which was going to be their starting point for tier four. But the new engine was a failure. Then Cat bought them and through out the new EMD design. They are starting over with Cat technology. Probably a good move since EMD has not come up with an all new engine design since they replaced the 201 with the 567 in the late 1930s. And then many of the difficult design features were actually developed by the GM research center.