The EMD SD70 is a series of diesel-electric locomotives produced by Electro-Motive Diesel in response to the GE Dash 9-44CW. Production commenced in late 1992^[1]
and since then over 4,000 units have been produced; most of these are
the SD70M and SD70MAC models. All locomotives of this series are hood units with C-C trucks.

Prior to the SD70ACe and SD70M-2 models, all SD70 models were delivered with the self-steering HTCR radial truck.^[2]
The radial truck allows the axles to steer in curves which reduces wear
on the wheels and railhead. With the introduction of the SD70ACe and
SD70M-2 models, EMD introduced a new bolsterless non-radial HTSC truck as the standard truck for these models in an effort to reduce costs. The HTCR-4 radial truck is still an option.

-Jagthunder's original Sd 70Ace design