 EMD began turbocharging the 567 around 1958; the final version, the 567D3A (built from October, 1963, to about January, 1966) produced in its V-16 form.As the 1960s opened EMD was compelled to respond to the challenge offered by GE's U25B, upgrading the features of their GP (General Purpose) and SD (Special Duty/Standard Duty) series locomotives, boosting the power of their 567 engines, then developing the more powerful 645 engines.Those endeavors as well as the feature upgrades introduced with the SD40-2 were sufficient to maintain EMD's competitive advantage over GE until the mid-1980s.